neocons 
—aeewt ow barca 
epee me Sa 
recone ib apace = 
aes —~ 
reread it 
Sarees CT =e eRe aes = 
cee ee aaa eames 
weonenaes faint -e~ ~0 
Seeeeneseet = . 
Ssemrenade Laie “= tpentarenteconeet SaaS ws - 
soenenn fale 
mrentgeane wary “maaeee nae aenAaSisaeNenn NS ERNSCELO = 
reusesenayocst 
mooceee son 
segeamen ace r ante 
meignene a-a0ec pperens 
neem Mo * Siecnoass 
pre eed: “arene near ato > 
peepee enetretaty— ea A RRS DSS for 
wane Sadat? sapeeangseemaneenaceaae gNANSEASOES a MS poe 
Solera ner re ener areraaeT eee serene on 
ON RT = ae . 
Paenan eR ocean F hm 
Sere seente erste As ~ 
weer inaiy if = 
nee — rs 
ee a een anne nee 
renege = + cornea 
ena ane mae 
— oa panier t 
ee a ~ one 
Sawa aL naaennannenae = Py arcane 
renee Semeeremnrmerereneeeres ; . : 
aan gened enone cond : 
Sasa a poe —— 
menveemenies Smee a — 
pane ina mana Seafarer Al: pe 
open aaa —ammnunate eather’ 
meena spear aera oceans wat vm re : = 
——— = = a a 
—— onan an = = Sys anaes _ 
oes orale —npemanyeeyeeenecnes') wi > = 
ee " Z : pom — 
a ~ “———— & es > ieunaaith - : 
ane rarer nen : ee — 2 —— " 
ane on ana . - “ r : 
any cee : “ Gavan oe = : men 
Smee “Tes, -rournaontansenayneonsnerecenasatbedaDGnngtenanaber angp oS cheeses Ras Seas Sapseetseae Sa ae = aes om PE PANTO TY Jncsaaneasenmnetenahe 
measwae pear es soonest Senenentae oe en peter etvenverrnene ear eear nearer eT peoeemeareneareneneeey 
nemees  6 s a en NR ALES CARNE Be =, - <= Ps _— paren RN eas 
See mere aan ceenaremanpaapeeairenieenaetate n= } en ae ee el TTT TA TE SSS TTS Ta aE 
oe a ee nn Sem = Hee cee = ERLE el ee - ee oe ~— PRN an tet ween amen emer. (A ee etter eee 
—evanet ac —nempanseamansvarudensansanteaupranentancnnnarean’ jprequranrs7F0 : : acne abs : Sa a ee eee. erat : aoe 
ene aeearnanannenetnaapenaarnaseaetntyr yearn = a * - je on =~ Sonia ere nenooesncopsgatant casas nencteneacorpangeee aenaenasaeaaee woes 
accent ar, Spenser aS MT nese MN > EN ait Se pe gna po tnt oe een eRe CPA ASE PERS SSPD CAT SETS cee NES AIEOT PSPS See SPT STS ASN SASSY SRN SESE ES SENT PROT 
— SLOTS = (oc iit. —— —s nas aor a 
ee a re seer 9 Ps —~* * " “< “ ~ enna ns es a, 
—-— ET Ge _—s ~~ ee a +~ - re —— 
eS, a SAAN eT seep — ee > = 2 
mn RR —T —— ai . 
seen (0Er peeneenrenenrmarvennreserraecmeannnennaneneennetty aan : ~ ~ — 
a ra RSE AE er oer EP rea sapere = — 
TT AAT STS SOIT - 
——or — 
enermmnavindente Sppteersremmnwterr-seermnenremereetn sonra 
SERENE er eres OEN 
—- oo moetnrarnreste 
a = — 
— 


| an 


— 


WHI 


HAMA 


itu 


vA 


int 


ET a 
(ee 
(ane err a ee 
a eee eee 
ere 
- ato 
eo} 
—— oo 
































mT 


i PEELOSEATS PEG ASL DE TPENTGESEES EET De OE LEET URI ES SERGE EAL EUE aS teabdere PAPSAP ESE EOS St ete UTE 
LHHELEATEL ERAT EA ATAU EE EU HEVEELSEAECUT EAT SLEET ED EAL EU EIST RE ETT PATEL ETAT EEC EE CG EPU ETL EEE itt 


f 


Tae 


CEEEEELLTELE EERE ELE 


THE UNIVERSITY 
OF ILLINOIS 
LIBRARY 


925 
V3ab 


Cop.Z2 Nee Foal te 
ae § . 


= a oye 
1 we. 


Return this book on or before the 
Latest Date stamped below. A 
charge is made on all overdue 
books. 


U. of I. Library 





JAN = "9 
—~ Ve atk * ~ 
her ee AUG 1 3 i965 


Ji 


MAYI939 | 


yur 13 i940 DEC TT WF 





8057-S 





BEACON LIGHTS 
OF SCIENCE 


a 
~~ ° 


Peetige: } 











SIDUAII Oo fwmapvo DUO14D 
"SUqUOLT Wn " Suk 2 . Pat NQ- 


Sy ta i 5s icy temiig tM 


UA ARS 


AS AVH 


pataitet He te 


SMW IA | & RSS. SEGEVIIHOW Z1LOUMY 2 I'd OddlH 


BEACON LIGHTS 
OF SCIENCE 


A SURVEY OF HUMAN ACHIEVEMENT 
FROM THE EARLIEST RECORDED TIMES 


BY 
THEO. F. VAN WAGENEN 


NEW YORK 


THOMAS Y. CROWELL CO. 
PUBLISHERS 


Copyright, 1924 
By THOMAS Y. CROWELL CoO. 


Printed in the United States of America 


INTRODUCTION 


In the following pages the attempt has been made to 
sketch, in outline, the development of Science throughout 
the centuries, in the lives of those individuals who, in their 
time, have contributed notably to its progress. Naturally 
it has been impossible to include all who have taken some 
part in the great work. And also, many of the most promi- 
nent are still with us, their labors unfinished. 

To the young man preparing himself for a scientific 
career, or entering upon its duties and obligations, the 
efforts of those thinkers and discoverers who have passed on 
and left to him the rich heritage of knowledge so far ac- 
cumulated should be an inspiration and an incentive. Or, 
taking a lower view of the matter, he should at least know 
enough of their lives to be able to connect the discoveries 
with the discoverers and to have some conception of their 
personality. We cannot be too mindful of the difficulties 
with which they had to contend in their explorations in a 
field of mystery, where none before them had blazed a 
path. 

Doubtless there were true scientists before Euclid. But 
of them so little is certainly known, and with their dis- 
coveries so much of mysticism has been blended, that their 
stories come to us enveloped in a haze through which it is 
difficult to arrive at a fixed starting point. It is also hard 
to draw a line which shall clearly leave on one side the con- 
clusions of speculation, and on the other the logical deduc- 
tions from correctly observed phenomena. It seems clear, 
however, that the habit of collecting and classifying ob- 
served facts of nature (mainly astronomical) began with 
the Semitic people, and from them passed to the Aryans by 
way of that first intellectual flowering of its civilization, the 
Greeks. But the latter lived in an environment so beauti- 
ful, and possessed—probably as a result of it—a tempera- 

Vv 


OG0UG73 


al Introduction 


ment so aesthetic, that cold-blooded study of nature was un- 
congenial, and to all but a very few impossible. If the con- 
tents of the lost Alexandrian library could be restored in- 
tact and made accessible to the modern student, it would 
no doubt prove of surpassing interest, but probably also 
of little value to science. 

As the glory of Greece faded under the stern shadow of 
Roman dominion, about all that the latter inherited from 
it, in the way of real knowledge, was the beginnings of the 
science of mathematics. Rome contributed practically noth- 
ing in its day to the explanation of natural phenomena, 
though it acquired a vast amount of empirical information 
through experience in dealing with its forces. And when, 
through the revival of mysticism, the Dark Ages came on, 
enveloping all Europe in their gloom, Science slumbered 
and dreamed for centuries, while Astrology and Alchemy 
wore its mask, and posed on the stage in the tinsel gar- 
ments of a dead and forgotten past. 

It is difficult for us today to believe that in Europe, for 
more than a thousand years, the children who were born 
into the world were taught by their elders that there was 
but one true source of knowledge—religion—and that it 
was not only useless but impious to seek for the explanation 
of natural phenomena elsewhere. When at last revolt 
against this monstrous misconception began, Science awoke 
from its long sleep; at first—as before—in the form of a 
revival of interest in the fundamental branch of mathe- 
matics, which was quickly followed by renewed activity in 
astronomy and mechanics, the two departments whose 
manifestations were most readily open to observation. 

Once recalled to life, other departments of knowledge be- 
came recognized in turn as they appeared as true children 
of science, and worthy descendants of those few masters 
among the ancients who, brushing aside as unworthy of 
their time the delights of speculation, devoted their 
energies to observation, and to the drawing of conclusions 
from the marshaling and classification of well demon- 
strated facts, rather than from the processes of ratiocina- 
tion. Yet the paths of these pioneers were beset with dif- 


Introduction Vil 


ficulties. Copernicus was proclaimed a heretic by both of 
the grand divisions of the Christian church, Galileo was 
compelled to recant on his knees, and Darwin of a much 
later time was called an atheist, though all were men of 
deep religious feeling whose lives were full of love and re- 
spect for their fellows. 

In arranging the order of these sketches, the life period 
has determined the sequence. With a few unimportant 
exceptions this brings to the reader in turn the different 
branches of knowledge as they were developed. Thus, with 
the exception of the early Greek studies in anatomy, mathe- 
matics, mechanics, and astronomy were the only sciences in 
existence up to the early years of the seventeenth century, 
when Mersenne, Harvey, and Gunter led the way with dis- 
coveries in acoustics, physiology, and magnetism. During the 
remainder of that period optics and physics were added. 
The eighteenth century witnessed the beginnings of the elec- 
trical, chemical, and geological sciences, and towards its close 
physiology and anatomy had become well founded on 
demonstrated facts. 

In the nineteenth century all these departments of re- 
search were greatly developed, and chemistry, the science of 
matter, easily took first place in importance, with physics 
a close second, and philology, embryology, meteorology, 
anthropology, ethnology, pathology, biology, and a host of 
minor ‘‘ologies’’ crowding upon the stage from the wings 
and demanding recognition. Towards its end, physies, the 
science of energy, displaced chemistry in importance, and 
at the present time is well in advance, while the thinkers of 
the world are reaching out into the new fields of psycho- 
physics and psychology in the hope—and the expectation 
—of being able to solve with their aid some of the mysteries 
behind those concepts of matter and energy whose laws and 
manifestations are now fairly well understood, but whose 
causes still remain unexplained. 


OOo 
August 1, 1924. 


Ue ae 
rey 
ie 


Pa ae N 

iy 2508) 1M ene 
buds WAl ag wis a 
ts BAL s 
ae 


, yy 
ts Pa Nie : 


¥ 
Het ale I crit 6 A a 
jena 


ip 
8% 
oe 


uf 


a 


» 


¥ 





THALES 
ANAXIMANDER 
PYTHAGORAS 
EMPEDOCLES 
DEMOCRITUS 
HIPPOCRATES 
PLATO 
ARISTOTLE 
THEOPHRASTUS 
ERASISTRATUS 
EUCLID 
ARCHIMEDES 
ERATOSTHENES 
ARISTARCHUS 
APOLLONIUS 
HIPPARCHUS 
DIOSCORIDES 
PTOLEMY 
GALEN 
DIOPHANTUS 


ARYABHATTA 
BRAHMAGUPTA 


AL KHUWARISMI 


AL HaZEN 
BHASKARA 
Bacon 
PEUERBACH 
MULLER (Regio- 
montanus) 
Da VINCI 
CoPERNICUS 
FALLOPIUS 


CONTENTS 


I. ANCIENT TIMES 


PAGE 
Erimitive: ‘Theones:') 7veuoid wants, cle see area ae 3 
Mathematics on oy. fecneui eae etre ee cceen + 
PEALE OUOTAY cc's sin a Sgro ae oe Maan ed Salk mle @atale 5 
JEVOUIIETONY Witla ini alas aos ae ditt ake sravevesalten racers 8 
INA TUTE POLODICO'! yf siayg lghuis! a bint ofale's\e ea eres 9 
PI BAICINGE Sirs Vale | Sale MGT ae idee Via wi eS 11 
Philosophy and Mathematics............... 12 
PUTS EI CLONOR oy) is tsa) a Mia's die o are! ae! a, shaaad a8 ess 14 
j SUN UEP ARN ie Ss SR A Be arb: Ge PR ee Dy, 
SA URUIIE VON Te eile iw viel sia, ax ey cathe 4 ater atevateelesd ais 18 
DVS LEMON UEGEL 4 pa ‘gk Garth Rie Aris: ce a eidlial ma aN 19 
IS COBO ica Puls gin 46 5 RAM thse a dle or erenee 21 
AEROMPOUAW Cate 4 e's a'ehd eis Micaela ie «ss <\'sl tation 23 
UU MERODEMING 1. 5'3 + iu th GRIMY IE ves ocd Wie Dahee ata 24 
CITA LICE ahs. os Sie ar EA Woe are b orwigan gee Sede 26 
PE POMC VV g'5. 5 iis aid MTS ne owas Ries goa de wee 27 
AOA TE OUR Ghats areas vind cvaed Pia aA Mlle dicts, ei aka \o wielooml 29 
Cosmology and Geographysceicis « siscsse ele 30 
GAEGINV oi knw intee stereo aia Malate oe’ x Glin mete lhe ale 33 
DIATOMS TICS «hwo. a.pincain A ofa ee Whee) male Bla laa die / ai 35 

II, THE MIDDLE AGES 
PAGEPOMONEN is ake aceda 'sailarbebt aioe ane bale ocaie etecaes 41 
I ENG ROS LICE L.'s «i use ey Me he oS! a ea vag araet atl 42 
BEGG EI STIGH foc sits eiel on REM NO aig: sy roll eae dea 3 
Pe POINT ICM sa) wets eigrar teint aiuaty ace Aisle stg DUN alone 45 
MathcriataGanns 1's sinew, oe aera crete ogra aah we aleing 46 
Speculative Philosophy and Natural Science.. 48 
PEACH OOIAUI Crane Fone didls | nate Saterday pices algee Eee ovens 52 
MGtNGmStGa! c. nianieiec dee muitei as dine ee cslewee ¢ 53 
CODOTR I CIENOG .'s cccotehe anions selec slew Stemiele 56 
PASELONGULV s calars-sd dbetaieta vbatanteiara/en asl eaaxveemtte 58 
ARACOTOV 0 sae s Wise ea he © biteleite bse te Hoinamenme 62 


Contents 


WI. THE SIXTEENTH CENTURY 


TARTAGLIA 
VESALIUS 
GESNER 
EUSTACIO 
FABRIZIO 
GILBERT 
BRAHE 
STEVIN 
NAPIER 
GALILEO 
KEPLER 
HARVEY 
MERSENNE 
DESARGUES 
DESCARTES 


IV. 


FERMAT 
GUERICKE 
TORRICELLI 
PASCAL 
BOYLE 
CASSINI 
MALPIGHI 
HUYGENS 
LEEUWENHOEK 
HOOKE 
NEWTON 
ROEMER 
LEIBNITZ 
HALLEY 
BRADLEY 
MACLAURIN 
DE JUSSIEU 


GRAY 
BERNOUILLI 
FRANKLIN 
BUFFON 
LINNAEUS 


Mathematics) io.'ss sc sis seis eeiaise be Sir eta pian 
ATACOMY hee telds cieies sais Bi viekeltiaws es tebi ee teleneiy etme 
Natural: History” ...'0), so s.se siecle ee uteens eine 
ADALODIY isis sib oi = 5's pypivies hiss) nee las ec 
ATISCOMIYy fa deems <5 bees tis Bee sn bles ea ee 
Natural (Science |.) ccs sac oes a se a 
ASEEOTIONIY. oy ie oss Lente etn Sate otk Bale sta eee 
Mathemticaies sisi ees stele «eee oa ee Cee 
Matheniaties ios istic ae oie a ie ee 
AStrODORIY: yrs oles ss GI Rs oe oe 
A SEPOT OILY) | os oj shini ssate'in ln ei ‘nd era elit ete ceate eee 
Physiology. ose inl, SESE Sade eles ore wee 
PUYBICS ie na ow bee ot cs EVIE oe aie a ee 
Mathoma ties). «ics bi a SES wo hew one tenn 
MGCDOMATICB 4 shel iatsidie’ vie" Ub) a ode ei ace 


THE SEVENTEENTH CENTURY 


Mathomatics) . 50's fe MUL ar ele ous ues, wie ane 
PHYSICS 6 i)s.0 le ano w'arsl ee UNDA Wnts eee ae an 
PR YSICR us o's bas p. sisiehn caete een oR Lee eee 
Mathematics v./.'4 4 24a eee ea = ev ee 
CHEM IBELY 9 6 o's oo o's clearer eae ot Sia bbe re ee 
AStronomy. \. 4+ sio0 pA. oneal e vies eae sie een 
AMAtOmUyyy 66: <a dn oe be eee ee ae os hee Se 
Physio Gila Pies Pate ele Biss Liens apsoet op ee 
Microscopy ies dc KP epee Cae ies s 54 ease 
ED YVSIOS oa i50 che osx ko ORR OR Dae o's ond a) tv 
PRY SiCE sie Caine Wie ib ba eee ew bcs se 
PRY SICH ya tnd bate tele ate Breck d <1 ey is 
Mathematics and Philosophy............... 
A pErOMOMLY, ee i$ isa sie eintepe lb an bleie «oi ote 
A SEONG « o'ld'o Rake Mtoe Syn ahs ha ee 
Mathematics ivie ads SPea ee ale aw tle thee 
BOtany ic6 a4 Hed ba Se ete bis eee chet ie ae 


THE EIGHTEENTH CENTURY 


CHOMISEDY: 456 6 oy 4 mnie, b Sierra wheel etapa 
Mathematics 
Bloectricity .\< «w. Skagen Aen es a Ce 
Natural. dlistory: «(5 G4 N25. Aui.. 2. aoe ee 
Natural History: Sts ee lee 


ooe eee errr ee eee eee seer eee ere eee 


EULER 
CLAIRAULT 
D’ALEMBERT 
HUTTON 
HUNTER 
BLAcK 
SPELLANZANI 
CAVENDISH 
PRIESTLEY 
COULOMB 
WATT 
LAGRANGE 
GALVANI 
HERSCHEL 
SCHEELE 
Havuy 
LAVOISIER 
LAMARCK 
VOLTA 
CHARLES 
MONGE 
BoDE 
WERNER 
BERTHOLLET 
JENNER 
LAPLACE 
LEGENDRE 
RUMFORD 
PROUST 
PRONY 
CHLADNI 
WOLLASTON 
DALTON 
CUVIER 
HUMBOLDT 
OERSTED 
Brown 
YOUNG 
BELL 
AMPERE 
AVOGADRO 
GAUSS 
Davy 
GAyY-LUSSAC 
BERZELIUS 
SILLIMAN 


Contents xl 

PAGE 

PEGLORISEICS Cavite lone lale CiciidisrSi a ateien ola wg seats 154 
Advi VTS REPRO RL RABID EEL EAA Le SPR SM EORDIE ce 8 156 
Bisthemin tiesy yn aaraciee ck va bic barnes 158 
AFOOLLY ish corsiertesn the nicl teal eRe ats foie wok ole lah 160 
Physiology) and) Anatomy site aihd 3s 4 Peleus 161 
CORBIS ERY, Vase ahasiis nisi wtelsti ate Waa. 'sie'aseyp essa w ea 162 
PoE Y BOLOMY clieces nc a reluctii a’ dighade Mid are W dik ohada lal y fete 164 
CSTE T Vas ete tie emia Wats ateha emis, wists veal oie iata 166 
(ORV BED Y hiatus adi le weneaerate aed a x 6 do aati 167 
Lidl $9 RC Babe ARBUART  Syr 9 en 1 SPN MRS Ss 169 
LCC UAMICE Weekes scoiepate wae DPE aia acd) oo id dines mlalale 171 
SCI VIRUGE hae to ohana eee ONE T Ie a) o's ooh mire ie We dgte 173 
PRTG LOLA pone eitin OR aD arene ead ins SA ae el aaa ad 174 
PL ECEOUOINY, Malsataietinu 6 wate onale aie esa h ested ata aes 175 
SSROMISERV: i wresieoline cue in at eae aed em athens NG Ae 
IE OLE fd aacieaiis suein SARIS Na AES Ya lave Uo ai dsc aR 179 
BVOISGEW ce arash; alts beiat ete Ox a aoe 6 o<5K a) eid Sd 181 
INSEUPEY TI ISCOTY: ssa lie ea ken awe 4,0) lee 's's 6 182 
PTICR TEOMA SH EINISEL Yo) 4(s sb iscvinin's i dhu Wass Malate Volo 4 184 
MOTB AULAEH Fu gia a losd dw acd a84 Ca Doig Bhi wep aes 186 
PAE GNIER 5s aia\y ashen sha eed ois ae Aw eke ae 188 
PAE CEISLGR ais Uk. cic cia Rial aye al MEN Ie: aati alo capare 190 
CPM ses sh S464 6 din yolorvas S88 AA MRTRINN as ek rd reg rere S 192 
MIRPRSER ST iotats airdigis ave g seal miala ale Me sla Seal vpe ale at abe 193 
EUAN AUTOM IL site ei die site age US Whale ahd vs, Wk alargia sacs pal 195 
PA MUTISIUGTINIY fh t14. "elm wis bie whe ala’ wraele twee a ele wee 198 
Ae SE EEROSIMEC ELSE | ah ss eas a'vc sav alichiahatina Wiayay ox, Sad at ak sears 200 
BE EIS «leva saa taialadeldes aga ret eva a era ne a aie s Ag SOs 202 
MS TRCRRIR AGE 5.0 sialon dna inl Wa NALS, sla ada r Da igtaeneha 204 
RELL ROTIALIC oe sos acess, averu slate GR atek an w kiedeimatatue 205 
Egg fo Utne Og TIMING RNY tr oALs PU SUR Rg 207 
CAPA UR recess tavcus ale bed eidcal UOTE aia wl ala to ba ae 209 
CORO MARE I ete) cS SIRE er aha cele u'a sated 211 
TRIO, sae tia xi else eR ARS tea Rae Wee IAN 213 
INBSUREL  ELIStOry janis ss alemedcnbain.c a's esis dokacat Cla 215 
LEM BAGG ey aiahessi ene ss. alain ahaa a Nhat Sherk aa cl Gab gears 217 
RoC PRAY, fu, danced sus saath okay Mo tmtai eB Mare wid rese a eee 219 
EAL Y ACE a a Neleta el al wie SPAN UOR MaRS he oi cay ace hw Weg Ait 221 
ALORA Y heigl hea dig AN HOPE TSE aig stk Aiei DS alla te 222 
MU VECERICICY ule svi vfelciaiata saa ee totahatah 0.47! as Wiel thatid at oe 223 
Be VEG Sa cased tavws italiana statataleis wiatalae yea x aianhs 225 
A PUROTIONILY ee 2s dar RC ne Peon aS ge) 229 
APHGUMIAEE VAIN ssid) cihisiadetcraaMerehe re wie ce Soe 5’ ocalederaletece 231 
SP REUIAL LY bates a gisghs aiave es atte iedate ok oe bs. Kip nates 232 
COR CTUS EEN icicle cleseisiare nin PION Gira ee alg ta wat cee 234 


SAU he oh se EMOTE IER. Athy “al olal a nacanate 235 


Xil 


AUDUBON 
BREWSTER 
BESSEL 
DULONG 
CHEVREUL 
ARAGO 
FRAUNHOFER 
OHM 
FRESNEL 
DAGUERRE 
FARADAY 
Von BAER 
LOBATCHEVSKY 
WEBER 
SADI-CARNOT 
LYELL 
HENRY 


Contents 


PAGE 
Natural) History» os 6.0 URSRy tea w> a cree ene 237 
PRY SIGS. 5 8s vies Yow webct Ok et eae 239 
ABtronomny (ssi ornithine sian eso eee 241 
Chemistry's V0 vss 4.0 dy oe oR ee ee 242 
Chemistry 35a aes shy cee Ea en eae 243 
Astronomy ns. oy os ~ ee AON Mae sees Eee 245 
PYROS yi a Rs e's i os ke ROG hee 247 
BALGCETICI EY: inn oy 50's GPRD freee otasie e 248 
Ved h a ite why eo Perera Ke ey} 250 
PHOCOSTAPHY 10) o4v swe se ieee geht 251 
FULOGETUCHGY i) bieih bist 0s SMALE SCAN taoe ingle a 253 
ERA TYOLO MY): 5/0), sss! eileen ele We ae eta 255 
Mathematles. ii \ii 5 ie cw shih aoe ee 258 
BBV SOLO RY 5.0 sil! e 44 iyo alata tah arta 259 
ERY BICB ie 6's p's\e'e 4. 0spe & Olde elbtahe Oe hag a en 261 
ROTOR Yi 6ie aim ibis A te sk ve ahi ME NO cee uae a 263 
Electricity < skis ga. wills Seale cent ah ene 264 


VI. THE NINETEENTH AND TWENTIETH CENTURIES 


DUMAS 
WOHLER 
MULLER 
ABEL 
WHEATSTONE 
DOPPLER 
LIEBIG 
MAURY 
AGASSIZ 
GUYOT 
DARWIN 
FORBES 
GRAY 
ANDREWS 
DRAPER 
LEVERRIER 
BUNSEN 
PACINI 
DANA 
BERNARD 
VON MAYER 
ANGSTROM 
HOOKER 

J OULE 
FOUCAULT 


Chemistry, ibs 5s s'Gigtwels oe elalneco a eee tara 269 
GHemIStr yi’. 5.48.4) s cc G88 ohana ie eee one ee 271 
PRyBiOlogy.. cs's ihe kins be aeieR ee e 273 
Matheomaties ..$ acy. iin 8908 ache ol ok oie rei 
PY RICE isis UV» Sc hikc. DCL Alc ee 277 
PHY Sies.) 5 divs is o's aia Ree ree te 2 ea 278 
Qhomistry. i.» 04)so24 yx seesieeiess «ae ee 279 
Geography \. ns sin aye Mae kh GG eee 281 
GeOlo gy). ins sm vidi, DANA IOLA ols 5 5 eee 282 
Geography i.i.o'«. Ue 2kbee eae Ge wees sas eae 284 
Biglogy) 24 sss eh ee ees se 286 
PhHYSICH) Vos WAN 4s HD on So bs bn ee 287 
Botany. J68 .'s6d 62 cas Me RU als en ee 289 
Chemistry sss. eielet. ks Ge N ehey oor Le eae 291 
Chemistry).'ssssy.boshe ae er eAle Wen > ho eka an 293 
Astronomy), a) <isicenss «cn seis eres «ic ee aa 294 
Chomistty. ¢sab sha twslekle ed viedetyis hen ete 295 
BWYBIOLORY (0c 4 = 4c SCORER AOE ee oie fg ca 297 
Natural ‘History, 644). (Gta, i iiee. 2. cee 298 
PWS, a :sis din nici Rarlan Ghe tates ee so eee 300 
ERYSICK: so s)n skin d eR Oe DE tee vie eee 301 
PED BICS. oka 55 oid. vin wtp earoh a arenas «ole eee 303 
B5OPOITY iw. no oo oo a ee et 5 306 
BAY BSIGS. s 54k Ws dss osc RETO a ss 4 ee 307 


PRYRICH) oi5/0 esd sh ae ha ea to ev A 309 


ADAMS 
STOKES 
TYNDALL 
MULLER 
HELMHOLTZ 
VIRCHOW 
GALTON 
WALLACE 
MENDEL 
CLAUSIUS 
PASTEUR 
LEIDY 
FABRE 
HITTORF 
KIRCHOFF 
THOMSON 
Broca 
HUGGINS 
SCHULZE 
BATES 
HUXLEY 
BUCKLAND 
BERTHELOT 
LISTER 
KEKULE 
MARSH 
MAXWELL 
TYLOR 
CROOKES 
NOBEL 
LUBBOCK 
WEISMANN 
LANGLEY 
MENDELEEF 
HAECKEL 
NEWCOMB 
LOCKYER 
HILL 
PERKIN 
ABBE 
GIBBS 
CoPE 
KOvVALEVSKY 
RAYLEIGH 
DEWAR 
KocH 


Contents xii 

PAGE 

ASLTONOMY: si ses/iie We idely felettra ik vie widtee sea ees 310 
BAY MOR vieja witch's hie wh BORER Ae tan eae te are 311 
BRYVSICE? i new mew Rome Sree ee ce trae er ae 313 
BROW ik Wikia wee bike's Got e aM ale She sia <cetala law OW is 315 
ED MICA be ce mimln ein Baers en area Man des HEE 316 
Pathology saad wis wai ohh ttre Pipa avis 6a oat d alal'erw tee 318 
1016S 9 ADT EV RECH, way. rey ss bis eins Soe couse ees 320 
Natral STLIstOry (hice itcin sige! dio einldj« sss cinta waa y 321 
BQO nix wreta we ieee Ne UH sib wala a ahsarateres 324 
PB YSICS) ins a clerbi be 8 nike Weare ees supe ow ain A are 325 
Baeteriglogy «vais ciwvks Joy ted aacue cwieaee un 327 
Natural EIstory ene petene a wee asics Gay Pea 328 
Natural istor yin in LG aie alae ens aia's acne es 331 
RVR snus ns Wini Se been Oe WIEN A ahd erate a aeons 334 
Ud gs Ce UAE at a peeenigy 8 BA PR OE 336 
PrP REO Si inte te bh se-b es bow Kine ere ld ore) ai bear Walalanet aa, ote 337 
ARALOULG stink note mien indole aniei abe o tbe Mhoel ald tae 339 
PRMGEDOIO Yd ie use a Wim ove pale Ld Sigel ah a roldtia Bree 6 340 
OIG PAR reese kiwaiclste tee yew eal’ a man’ 342 
DV ALUTOLRERIGLOTY (ANG. ADM eee an sia bid eee tee 343 
EOIN Vue lee ehh tree iit al bla a ciate Bee 345 
ING CALA EERIE Ye peck tenre opie een hare ata Niet tat aw ate 347 
JEU EU Leek Bi Aa Lr ER PROP AR 349 
PAOGICAIEY elitalaig dieiete sai Ped dae are wa whee Ne 351 
MNT trees Sie Ril weld Biel wild ala Glee gia blag 353 
EERERTSE RUSSUOT VO saa Fieia te OREE Na ig tate’ Pedals 354 
Ee VOLCR Valse g wi drcbaa ate Cigvescs ur eset allel ate eighar ae & 357 
PMOL VT aidan ea at ese adele wis yeaa 358 
Re EG UCEEY pip wi apa erates alaiahel a has ete oka ieee a ale cae’ ake n aia &¢ 360 
PASM CLOBEY Crd ats igeis B's an gia aia Pale Cale tat 362 
INGTALERD EEARCOTYS va 2514 ic outatatetot nets aisle sin cela 364 
POULOLY Praca bias std alates boca bE Re eRe Seale ek 365 
PA VISIRIIEL aches aot unl ac awh Sia aie eleie ws ole Alen aeale aes 367 
BULGTNERGY Ye lead pos tha dni k's pier eae avenged dats 368 
PAVOMLGIOTE Hs Gini tia'dl diphaacaie aerate ape anes, 4.x. aie a 4 Or Means 370 
NESERGMIALICS 5 05 sl5 aici p aye Gyermiaiiais meine Vike wine's 371 
ASETORD ITY osu cinta wine atiits Chala ele ak 4b sate aes 373 
VABLLOROU Wil pap Give wis hy me a etanteNe eyed iy cea th 375 
SR AEGIRLE Ty c/a wiaaigne cadets eure Mite ei gexle wake ects 377 
MGTBGTOIOR VE sie dy iataiteee srett kde aiiela'p @ fol wieiia ais 380 
NIGChOminties eS Fis cycle ee A eS oo wk we oles 381 
INSUMTALETLIBLOEY mera i dicic areata a ee a ese WPA Se fine 383 
PEON VOLO PY fate cia tro aul dia toe Bt ee ky al elelec ae 385 
PD VSICHN ana aictate Ue ghoie Deets BRIE Gein dea tare ae 8 386 
PIVESCS vod aiehis screech chy aT Rig ek SA he tare 388 
PIGCTOLUMOTY Valin se wsnur tei a NR ns sic nshe else a 390 


X1V 


MICHEL-LEVY 
BOLTZMANN 
METCHNIKOFF 
WROBLEWSKI 
ROENTGEN 
EDISON 
ROWLAND 
MOISSAN 
FISCHER 
RAMSAY 
BECQUEREL 
VAN’T Horr 
THOMSON 
HERTZ 
ARRHENIUS 
BRAGG 
ZEEMAN 
STEINMETZ 
CURIE 
MARCONI 
EINSTEIN 


Contents 


GLOOM O RY rein as o's ance Sethe ie eta 
PDYSICE suis isso cies bse Bian eee 
BIOLOGY Gals whte ssh «dino else rear le 
PRYRICS ck es encase oo ee ee 
PAY RGSi ie osha oi osm oc 8 oe Ee oe 
TE OCEXECLON, Fcie'e, ive o/s a ere termite a 
EI RYRICH fs eisivints + die la, cm eee Reis SIRNAS 
ChOUMHAETY cc 6 a esshs akin eos Cuneta 
CHONUISEF Y's 'ss olee's eke ete bene 
CREMISEEYV C0. 'y ¢ o's cee c's sa ee 
PRVRIGS Thi cig ty «win. ris Chere ina aie iain 
CHEMIBETY, bin bis'sln sole Goth steel bum ane 
NOLOCERICIES co's ale W'wrnieis bm tee AON eames 
PP INVRIOR ak a uig back & e sin ete one nee 
CONGMISHIY Os; nip se ope diel ee Rie 
PPRVEIOS \Gin'o ace ure aca Hit © ane ernie ee 
PHYSICN) ie bis ee ecieees Clee ee 
HSIBEGEICILY pine Bi oie st wie ols eee en 
CHEMISTRY, 0. Ss, «enon nie eRe 
Bloctricity’)\.\s ise 's\cmeiemtsae a 
PURYRICS) sp 5's oe bie ecto Meee en 
Lt 01> Nae ene Wee ae OMA ee Tr Pee Ror AnbeRRAy gs 


ILLUSTRATIONS 


“THE FOUNDERS OF SCIENCE” 


The above is the caption of a series of bas-relief portraits in bronze 
decorating the new million-dollar building of the National Academy 
of Sciences and the National Research Council, in Washington, D. C. 
Thirty-seven world scientists were chosen, only two of whom were 
American. 


HIppocraATEs, ARISTOTLE, ARCHIMEDES, COPERNICUS, VESA- 


PRUIG EPREVIY ass gained aes de Sie wie aie gaa oseee frontispiece 
PAGE 

GALILEO, LEoNARDO, Hipparcuus, Evcuip, Democrirvs, 
BUMS see ssath shade ules MN sala cde: G9: cles ae OUI Rae ELAN ALY 


CaRNOT, BERNARD, JOULE, PAstruR, MenpEL, MAXwELL.... 140 
Humeoupt, DAtton, LAMARCK, WATT, FRANKLIN, HuyGens. 210 


Descartes, Newton, LINNAEUS, LAvorsizr, LAPLACE, CUVIER, 
GAUSS eoeemwepeeeeeeeeeeeeeeeeeeeeseeeeee eeeeeeeeseeee eeee @¢ 290 


GauTon, GiBBs, HetMHoutz, Darwin, Lye, FarapAy..... 380 


















‘a ; 4 ss ' 7 
ny : ’ A ‘ ran © “ee 
Shel 4 di + oe i ua (ane | yb \ 
“dh Ay r i "Wik Ge - Yh? 
word ‘ i y r i 7 3 
ira Shoe 8 ie § 3 aes v 
" <1 i Hh rt ta ine td) be 
rs ; : 
5 he Ps 7 : 
An ‘ 
: j ¢ : 
bat 
. , } 
mety)! : 
‘ , Lo vai 
' ie \ 
Oki Saat Nt 
: if hy Wi ih ' ; 
\ ite yi 
i reshs) ; 
J 
hs y 
i 5 . te 
’ hee i 
N ’ 
Wi 
a! 
vy 
{ ; 
} : 
} ‘ L fF ; - ‘a 4 an é 
t j f Py 
oy tive SG Fo) fe Xa | Mer aee we ON aR Ree ean My d ae 
‘ ‘ \ .f ; i ' 
‘y ay ; ty 
‘ : yf rn aa er, mee | 
4 } : p im || oe. ach fi 
fit ; n ‘ eA Wh ry. a mh y cay, gees A 
: 5 is nl } iS Tat r ‘ ' 


A 4k AL OE 





ve r - a we 


‘ < 





tw ec eas ee by 
s 

















AP Phu CHER 
te 2 iy ‘ M 4} ny 


iy 






J 
ANCIENT TIMES 


For the purpose of this volume it will be convenient to define 
its first department (Ancient Times), as the epoch extending from 
the beginnings of recorded human history, up to the fall of the 
Roman Empire in the year 476 of the present era, a period covering 
certainly 6000 years; for inscriptions that are clearly alphabetical 
in their character appear on many of the Egyptian and Chaldean 
monuments, whose age has been determined as early in the 5th 
millennium B.c. And before them for an unknown time were the 
years of hieroglyphs. 

But we may safely deduct at once at least four millenniums from 
this reckoning, as a period during which the art of writing was 
confined wholly within the priestly class, and employed only to 
record the principal acts of rulers, or startling occurrences like 
famines, floods, eclipses, etc. And about as safely another thou- 
sand, for the slow development of a script convenient enough in 
execution, to permit of the recording of conclusions arrived at by 
observers of those natural phenomena that were daily presented to 
the senses and minds of the civilized people among the ancients. 
This brings us down to a date somewhere between 750 B.c. and 
500 B.c., at which time appeared Thales of Miletus, the first of 
whose story enough is known to warrant his inclusion in a list of 
scientists—that is, of collectors and classifiers of observed phenomena, 
apparent or real. Certainly there were students and scholars before 
his day, for by then much true knowledge of various kinds had 
accumulated, but their names and their histories have been lost. 

During the eleven hundred years remaining of the period, namely, 
from 624 B.c. to 476 a.D., history has preserved less than a score 
of names worthy of enrollment as ‘‘Beacon Lights of Science.’’ 
It is a significant fact that, of the total number, sixteen belonged 
to the Greek race, the other two, Thales and Ptolemy, being re- 
spectively of Phenecian and Egyptian ancestry or birth. And, as 
showing the versatility of Hellenic culture, four of these attained 
eminence in mathematics, four in astronomy, two each in botany 
and the healing art, one each in general philosophy, mechanics and 
anatomy, while to Empedocles must be accorded the supreme honor 
of having formulated the first known conception of the theory of 
evolution. 


BEACON LIGHTS OF SCIENCE 


THALES (cirea 624-560 B.c.) 


PRIMITIVE THEORIES 


THALES is reputed to have been a native of Miletus, a 
very famous ancient Greek city located on the western 
eoast of Asia Minor at the mouth of the Maeander river. 
By race he was of Phoenecian ancestry. He seems to have 
been possessed of engineering capacity, for he was en- 
gaged to construct an embankment along a portion of the 
shores of the river Halys. He was also a merchant of 
importance, and traveled extensively, particularly in 
Egypt, where he became familiar with such astronomical 
and mathematical knowledge as by then had accumulated 
among the priesthood. In consequence, upon his return to 
Miletus, he was able to predict an eclipse of the sun, which 
actually occurred in the year 585 B.c., and acquired thereby 
a great reputation. Being a man of wealth and leisure 
he decided to devote the balance of his life to philosophy, 
and was regarded either then or later, as one of the six 
or seven wise men of ancient Greece. 

He taught that the fundamental element of which all 
things was composed was water. That the earth floated 
upon it; that it was the cause of earthquakes and volcanos; 
that it was the main component of all vegetation—which 
apparently could not exist without it; of all animal life 
that lived on vegetable food, and hence by necessity, of all 
flesh-eating animals, including man. According to some 
of his commentators he regarded earth (soil and rocks), 
air and fire as also of elementary character, though of 


3 


4 Beacon Lights of Science 


secondary importance. He is credited with having be- 
lieved that the earth was of the form of a sphere, and that 
the year consisted of exactly 365 days. He expressed his 
views in words only and committed nothing to writing. 

Thales, whether a real or a legendary character, repre- 
sents the beginnings of Greek intellectual life. Before his 
day much information about the ordinary phenomena of 
life had been gathered in Egypt, Chaldea, Phoenecia, and 
te a lesser extent in India and China. But life was hard 
and unlovely among all those people, for they occupied 
regions where climatic conditions were severe, and the 
struggle for existence a pitiful one, except for the favored 
few. To the Greeks, however, had been given a pleasanter 
homeland, a more genial climate, and an environment that 
encouraged thoughtfulness and a desire to understand the 
causes of things. As their civilization advanced, a very 
considerable percentage of the mass of the population lived 
in comfort and comparative luxury. Out of such condi- 
tions arise appreciation of the beauties of nature, and a 
desire to produce beautiful things, in other words, the 
fine arts. Also a tendency to speculate about the mysteries 
of life and the universe, but without any observational 
foundation. These were the impelling and prevailing ten- 
dencies in Grecian life until the time of Aristotle (about 
350 B.c), who taught a more correct way of looking at 
things. 


ANAXIMANDER (610-546 B.c.) 


MATHEMATICS 


ANAXIMANDER was born at Miletus, one of the populous 
and famous ancient cities of the western coast of Asia 
Minor. Very little is known of his personal history be- 
yond the fact that he became, after the death of the 
philosopher Thales, the head of the Ionian school of Greek 
thought. Aside from the reputation which this position 
brought to him, he is generally credited with having been 
the first among the ancients to proclaim that the axis of 


Ancient Times 5 


the earth must be inclined to the extent of about 23 degrees 
to the plane in which it stood (or moved) with respect to 
the sun. In other words, he taught as a fact the phenome- 
non we now call the obliquity of the ecliptic. Yet there 
is no clear evidence that he had any true conception of the 
shape of the earth, of its revolution on its own axis, or 
of its annual journey around the sun. Yet he is believed 
to have been the inventor of those old astronomical de- 
vices the gnomon and the polos. The views of the cosmos 
held in his day were full of strange contradictions. It is 
difficult to believe that a mind capable of reaching so 
close an approximation to the cause of:the annual change 
of seasons, and of producing an instrument capable of 
indicating divisions of time by the changing positions of 
the shadow it cast, could have been wholly unacquainted 
with the causes behind these results. But, as was the case 
with most, if not all of the Greek philosophers, Anaxi- 
mander seems to have held and taught, along with a few 
eorrect facts of Nature, many others that now seem ab- 
surd. For instance, his conception of the Universe appears 
to have been that of at least three concentric transparent 
and revolving cylinders, to the outer one of which the sun 
was firmly fixed, while the middle one carried the moon, 
and the innermost one the stars. Within these was the 
earth, also cylindrical in form, and either stationary or 
moving with the others. He was uncertain as to the posi- 
tion of the five planets then known. On the other hand, 
according to some of the ancient writings, he made some 
excellent approximations of their size and relative dis- 
tances from each other. 


PYTHAGORAS (ce. 580-500 B.c.) 


ASTRONOMY 


SucH accounts as have come down to us of the life and 
activities of this traditionally famous Greek, are not at 
all clear, and much is plainly pure myth. He appears to 
have been a native of Samos, an island off the west coast 


6 Beacon Lights of Science 


of Asia Minor; but of his ancestry and of his youthful 
years we have no reliable information. In his early ma- 
turity he appeared in the city of Cretona, in the southern 
part of Italy, which at the time was the seat of a Grecian 
colony. Here he founded a society or brotherhood, of the 
nature of an intellectual autocracy, which later took on 
a political cast, and became deeply involved in the fierce 
struggles then in progress throughout the Grecian world 
between democracy and plutocracy. In the end the few 
Pythagoreans who survived were driven from the country. 
It is not known whether Pythagoras escaped before the 
culmination of this event, or perished in it. Whichever 
was the case, Pythagorism represented subsequently some 
very strange conceptions of the Universe, which have come 
to us through contemporaneous and subsequent writers, 
but so alloyed with fable and nonsense that students of 
Grecian history and thought have found it very difficult 
to decide with any degree of certainty much more than the 
outline of his teachings. Not a word that could be safely 
ascribed to him personally has been preserved, and of the 
writings of his disciples we have only fragmentary re- 
mains. From these, and from later writers, two of the 
more startling of the tenets of the cult appear to have 
been as follows: : 

As to the substance of the world, they conceived it to 
be composed of material atoms, each one of which was so 
infinitesimally minute as to represent position only, without 
size. Two, side by side, expressed a line and conveyed the 
idea of direction, but again without magnitude. Three 
(one being at right angles to the other two) indicated 
surface, but without thickness, thus being merely the rep- 
resentation of area or extension; while four (the fourth 
at right angles to the other three) constituted a solid, or 
the conception of Form. Thus the three-dimensional prop- 
erty of Space was reached and explained. It was regarded 
as unlimited in extent, and filled with air, or, according 
to others, a void. As to the atom, if it were of earthy 
matter it was believed to possess the shape of a cube; if 
of fire, that of a tetrahedron or three-sided solid; if of 


Ancient Times i 


water, that of an icosahedron or twenty-sided figure, while 
those of all other substances were twelve-sided masses. 
Out of all this rubbish the only item of importance is the 
conception of the atom as the ultimate component of mat- 
ter. 

In regard to the external Universe, the Pythagoreans 
taught that at its center there was a source of light and 
heat in the shape of a perpetual and intense fire, and that 
all the heavenly bodies—including the earth—revolved 
around this in concentric circles at various distances apart. 
That the earth was the nearest to this source, and made 
its revolution in such a way that one of its hemispheres 
always faced this source (just as one face of the moon only 
is presented to the earth), and was necessarily uninhabit- 
able, on account of its intense heat. All the other celestial 
bodies shone by reflected light only, the earth obtaining 
its share by reflection from the largest of them, the sun. 
When the earth is on the same side of the central fire as 
the sun the phenomenon of daylight exists. When it is 
on the opposite side, that of night supervenes. 

These examples of Pythagorean philosophy are suffi- 
cient to show that its founder and his disciples were people ~ 
gifted with vigorous imaginations, but poorly equipped 
with demonstrated facts; just such a combination as might 
have been expected of the lively and speculative Greek 
mind at that age of the world; so different in its nature 
from that of the still older Egyptians and Babylonians, 
each of whom developed theories of the Universe of a very 
different kind. 

Whether Pythagoras ever existed as an individual, or 
whether the name simply stands for a system of philosophy 
having for its object to account for the innumerable mys- 
teries of existence, the cult very properly takes its place 
among the beginnings of science for, in spite of the mass 
of error it stood for, here and there appear conceptions 
and conclusions that have since been demonstrated as re- 
alities. 


8 Beacon Lights of Science 


EMPEDOCLES (495-435 B.c.) 


EVOLUTION 


Tus Greek philosopher was born of a distinguished fam- 
ily whose home was in the city of Agrigentum in Sicily, 
when that island was a Grecian colony. In addition to 
having attained a high standing as a physician, he is re- 
garded as one of the notable philosophers of the ancients. 
He also appears to have been a strong advocate of certain 
political doctrines of a democratic tendency, which he en- 
deavored to put in practice in his native city. Very little 
reliable information of his life has been preserved, but 
many marvelous stories have come down to us relating to 
his beliefs and ideas, and to his powers as a physician. 
The most of these are simply exaggeration, though perhaps 
based on real facts of a less startling nature. Of the 
manner of his death several tales are told. The most com- 
mon was to the effect that he leaped into the crater of Mt. 
Aetna. Another states that he experienced translation, 
after the manner of the Jewish prophet Elijah. He is 
said to have performed several miracles, one of which was 
to bring back to life a young girl long dead; and another 
to avert from Sicily a pestilence raging in southern Italy, 
by compelling a change in the direction from which the 
wind was blowing. 

Amid all this legendary nonsense it seems to be a fact 
that he was one of those early thinkers who had grasped 
some germs of the idea of evolution, in his endeavor to 
account for the mysterious phenomena of the Universe. 
Aristotle was another. With Empedocles the theory took 
form in the saying that ‘‘Nature produces those things 
which, being continually moved by a certain principle 
contained in themselves, arrive at a certain end.’’ To 
connect the rather obscure meaning of this sentence with 
the modern doctrine of evolution requires some knowledge 
of the brand of philosophy he represented. He held that 
‘‘Being,’’ by which he meant Matter, was eternal and im- 
perishable. He considered it to be of four kinds or ele- 


Ancient Times 9 


ments mutually independent, namely, earth, air, fire and 
water. He maintained the existence of two fundamental 
and opposing forces, which he typified as Friendship and 
Strife; the first of which was the indwelling and normal 
principle, and the second the external and abnormal one. 
These two, in their perpetual conflict, the one to maintain 
the status quo and the other to change it, produced all 
the phenomena of nature. He held that these changes 
were constantly and imperceptibly occurring, and had 
been throughout unknown ages in the past, with the effect 
of steady progress upward in all phases of existence. 
Finally, that man was, at the present, the highest product 
of the process. In thus indicating that the principle he 
ealled Strife—by which perhaps he intended to convey 
the idea of competition for existence or supremacy—was 
always in the end victorious, he may have grasped the 
germ of the idea at the foundation of Darwinianism, the 
survival of the fittest. With Empedocles chance, or acci- 
dent was the cause of the successes of Strife over Friend- 
ship. Aristotle rejected this as of the nature of an impiety. 


DEMOCRITUS (cirea 470-400 B.c.) 


NATURAL SCIENCE 


THis notable Greek, whose birthplace was the ancient 
town of Abdara in Thrace, went by the name of ‘‘The 
Smiling Philosopher’’ among his intimates, because of the 
geniality of his disposition and his optimistic temperament. 
About all that is known of the details of his life is that 
he was a man of high moral character and strong religious 
tendencies, was well educated according to the standards 
of the time, was deeply interested in mathematics and 
astronomy, wrote extensively on these subjects and on 
philosophy, and had traveled through much of the civilized 
world of his day. Only fragments of his writings have been 
preserved. These were collected and published by Mullach 
in Berlin in 1843. From them, aided by references in, and 
commentaries by other writers—both Greek and Latin, it 


10 Beacon Inghts of Science 


has been possible to deduce the general system of philoso- 
phy which he held, and probably taught. 

It was based on a theory of that aspect of matter which 
the mind receives from the five senses, the essential nature 
of which has been considered, until recently as unknowable; 
but which now seems to have been resolved into one of the 
manifestations of the equally unknowable entity we call 
Energy. In his system a material atom was postulated, 
infinite in multitude, not all of one size or kind, but each 
endowed with the power of motion, and the ability to unite 
into aggregates of all dimensions, forms and quantities, 
under certain pre-ordained laws; some of which eventuated 
in the phenomenon of life, and others in static con- 
ditions, which were apparent in those manifestations like 
rocks and metals, which plainly lacked the vital quality. 
For these reasons his philosophy was known among the 
Greeks as the Atomic System. To Democritus therefore 
belongs the credit of having first conceived the idea of the 
material atom. 

To what the theory led, and what speculative structure 
he reared upon its foundation, is not clear. He denied 
the existence of Design in the Cosmos, but asserted that of 
immutable law. Animals, vegetation, moving air and water, 
he regarded as combinations of atoms of average quality. 
Consciousness and thought the product of the coming to- 
gether of particles of a finer kind. And he postulated the 
existence of a third and superior class, of which the sub- 
stance of the High Gods was composed. Happiness he 
considered as the supreme object of existence. To attain 
it, the passions must be controlled, and temperance made 
the rule in all departments of life. As to a possible future 
stage of being, he seems to have had no theory. 

It is thought by some students of the Greek mind that 
Epicurus (circa 324-270 B.c.) was a believer in his philos- 
ophy, and taught it, with probably some amplifications of 
his own. According to him, fear of the Gods and fear of 
death were the two great destroyers of human happiness, 
and the main objects in life were to overcome these terrors, 
by rising superior to them, Believing that Personality 


Ancient Times 11 


ended with death, he argued against looking to the future 
for any amelioration of present condition; insisted that 
hfe was wholly an affair of to-day, that it was beautiful, 
that it was the summit of wisdom to enjoy its gifts as they 
eame, but always temperately, and with consideration for 
others. He thought that the gods were imperishable, and 
could have nothing to do with us, inasmuch as they lived 
on a different plane. If these were also the ideas of 
Democritus, they were rather above the average of the 
time, but have little value for the present. 


HIPPOCRATES (circa 460-375 B.c.) 


MEDICINE 


HIpPPocraAtEs, the most celebrated Greek physician of his 
time, who is called the Father of the Medical Art, was 
claimed by his contemporaries to have been the seventeenth 
or nineteenth in direct descent through his father from 
the mythical Aesculapius, and through his mother from 
the equally mythical Hercules. He was a native of Cos, 
one of the Aegean isles, where he practiced his profession, 
and was at the head of the medical school there until old 
age compelled retirement. Much of his supposed history 
is undoubtedly fabulous and unreliable, but that he was 
an unusual man for his time, and held some very advanced 
views in anatomy, and on the treatment of diseases, can 
hardly be denied. The latter, broadly, took the form of 
a strong reliance on the forces of nature, and on the power 
of the body itself, to eliminate or overcome disorders even 
of a serious kind, if aided by proper regimen and improved 
environment. With this was coupled an equally strong 
disinclination to interfere with the normal functions of 
the organism by the administration of drugs. Thus, he 
often prescribed merely a change of climate, or an altered 
and limited diet, or the securement of conditions that would 
provide absolute quiet and long hours of sleep. Frequent 
bathing of the entire body, sometimes in cold, and at others 
in warm or hot water, was also a favorite method adopted. 


12 Beacon Lights of Science 


It was probably this very sensible system which, as is now 
well known, will cure a very large percentage of human 
bodily ills, that brought him the high reputation accorded 
by his contemporaries. 

The writings that bear his name are seventy-two in 
number, but many of them are now ascribed to his sons, 
Thesalus and Draco, and his son-in-law, Polybus, all three 
of whom were his assistants in‘ his practice. The fifteen 
to twenty that are considered actually his are marked with 
a sanity of view and an absence of mysticism unusual for 
his age, and point to the conclusion that his reputation 
was well earned, though probably not so astonishing as 
some biographers of his time and since would have us 
believe. 


PLATO (427-347 s.c.) 


PHILOSOPHY AND MATHEMATICS 


THE real name of this Greek philosopher was Aristocles. 
He was a native of Aegina, a small island just off the 
southeast coast of Greece, and a dependaney of Athens. 
His parents were large land owners of the upper class, and 
in consequence he was given the best education that the 
times afforded, the most of- which was absorbed at the 
Lyceum conducted by Socrates. Of the details of his life 
little is known, but according to tradition he distinguished 
himself as a youth in athletics, and was a composer of 
poetry. But none of his productions in this line has been 
preserved, for at the age of twenty he became so interested 
in the philosophy of his great teacher, that he is said to 
have burned them as unworthy. He was so affected and 
even embittered against the authorities of the time at the 
judicial murder of Socrates, that it is thought he left 
Athens shortly thereafter, and spent the following ten to 
twelve years in travel in northern Greece, southern Italy, 
Sicily, Libya and Egypt, in the seareh of a civilization 
where more liberal and friendly and honest conditions pre- 
vailed. Of the truth of this quest there is no clear evi- 


Ancient Times 13 


dence, but in the year 387 B.c. he was again in Athens, at 
the head of an organization called the Academia, which 
held its meetings in a public garden or grove outside of 
the city, that formerly had been a semi-sacred place, dedi- 
cated to the memory of a mythical hero named Academus. 
There, for forty years, and until his death, Plato taught, 
and discussed with his pupils the questions of the day and, 
as was the custom of the time, instructing them during the 
periods of recreation in athletics, on the theory that the 
body and mind should be developed together. Among his 
more famous pupils were Aristotle, Demosthenes, Lycurgus 
the financier and Eudoxus the astronomer. It is believed 
that Plato exercised unusual care in admitting students 
to his lectures, and refused to take pay from them, on the 
theory that Truth should be imparted freely to all who 
were earnest seekers after it. 

His standing as a scientist rests primarily on the well- 
attested fact that, for his day, he was a mathematician of 
a high order, though not a discoverer of any new prin- 
ciples in numbers, or the developer of any new system of 
working with them. Nor did he teach it directly. In 
fact no one was allowed to attend his classes who had not 
already become fairly proficient in the science. Regard- 
ing it as the one department of knowledge in which certi- 
tude of result could be obtained where correct premises 
had been employed, he endeavored to lay the foundations 
of a system of philosophy which could be depended upon 
with equal confidence. In this he attained a certain degree 
of success, yet by no means a complete one. For, though 
we can today read much of his writings with advantage, 
and admit the possibility of some of his conclusions, the 
best thought of the world at present is to the effect that 
certain conceptions of which the human mind is capable 
are scientifically unknowable, in the sense that their parts 
cannot be assembled, classified, grouped and organized into 
a coherent body of demonstrated fact, that can be relied 
upon as long as it continues to be satisfactorily explana- 
tory of observed phenomena. 

In a day when polytheism was the accepted religion of 


14 Beacon Lights of Science 


the educated, Plato taught what may be described as a 
pure theism, that is, belief in a Deity related closely to all 
living things, vegetable, animal and human, but at the 
same time he made no attempt, toydefine the nature of the 
relationship and, in fact, asserted that definition was im- 
possible. Beyond this in religion he did not go. But in 
ethics he felt justified in going to great lengths. 

Plato wrote very extensively. But much has been lost, 
and much that was originally credite@ete. him is regarded 
as spurious by present-day students. Rejecting the latter, 
the fundamentals of the philosophy he taught seems to 
have been about as follows: 

Truth is hard to find, and in many cases impossible; but 
it is wise to discuss it in all its aspects Hecause, by such 
a treatment, much of error can be avoided. 

As to conduct, which he ealled the ‘‘ Royal Art,’’ he re: 
garded it as a science, which must be learned through 
experience, just like a material art, as carpentering. Its 
basic principle, self-sacrifice when necessary, once grasped, 
must be obeyed relentlessly to the end. 

Plato was inherently a metaphysician, and metaphysics 
is regarded today as a diversion, which leads nowhere, and 
to nothing except temporary mental amusemertt. In other 
words, it is not common sense to the average human mind 
as at present constituted. As it may with reason be as- 
serted that individual mentality has evolved to a higher 
state than was existent among the Greeks, his philosophy 
ean be admired as among the most advanced of that time, 
his ethics can be commended whole-heartedly, but many of 
his conclusions should be recognized as adolescent in char- 
acter, and below the standard which should be held now. 


id 


‘ARISTOTLE (384-322 B.c.) 


NATURAL SCIENCE 


THE distinguished thinker, Aristotle, was a native of the 
ancient Greek city of Stagira, which was situated on that 
curious three-pronged peninsula projecting into the Aegean 


Ancient Times 15 


sea to the south of the present city of Saloniki. In olden 
times the region was a part of the kingdom of Macedonia. 
He belonged to an aristocratic and wealthy family in which 
learning had been hereditary for many generations, his 
father having been court physician to King Amyntas IT. 
He received the best education that the times could afford. 
At the age of seventeen he went to Athens and associated 
himself with the school of which Plato was the head, and 
studied under that great teacher for nearly twenty years, 
becoming towards the last one of his chief assistants. 
After Plato’s death Aristotle moved to Mysia on the north- 
western coasts of Asia Minor. Three years later, just be- 
fore the capture of that place by the Persians, he removed 
to Mitylene, the capital city of the island of Lesbos in the 
Aegean sea. In 342 B.c. he moved to Pella, then the capi- 
tal of Macedonia, and for the next three years supervised 
the education of Alexander, the presumptive heir to the 
throne, who later became Alexander the Great. When, by 
the death of his father, this youth became king, Aristotle 
remained seven years longer, attached to his court, and 
held in high esteem by his former pupil, to whom, in that 
period, he acted as an adviser. 

In 334 B.c., at the age of fifty, Aristotle returned to 
Athens, and opened a school of his own, which at once be- 
came famous, and where he taught for twelve years until 
the death of Alexander in 328 B.c., when he moved to the 
city of Chalecis in Greece, and gave up his school in the 
attempt to recover his failing health. There, however, he 
died in the following year, at the early age of sixty-three 
years. 

Aristotle was probably the most voluminous writer of 
ancient times. In his works he dealt with almost every 
subject of which the people of his day had knowledge, or 
thought they had. These included religion, law, logic, 
rhetoric, metaphysics, physics, astronomy, meteorology, 
natural history, botany, zoology, anatomy, medicine, me- 
chanics, ethics, politics, physiology, psychology, poetry and 
literature in general. In matters of science (except mathe- 
matics and geometry) his works have no value at the pres- 


16 Beacon LInghts of Scvence 


ent time, yet all of them exhibit remarkable analytical 
power, and such as have come down to us either in part 
or complete, have exercised an enormous influence. In 
many cases he gave expression to thoughts and conclusions 
which contain germs of discoveries made since. Perhaps 
the most notable of these was his speculation on origins 
and growths, which come very close to the fundamentals 
that are at the basis of the theory of Evolution. Accord- 
ing to him, Being, or Existence, was the summation or 
visible expression of four universal elements or principles, 
which he named as Matter (in all its manifestations), 
Form (in all its variation of shape), Causes (active forces) 
and Results (evident effects). At the beginning of things 
he postulated a definite plan which, at the end of things, 
was to produce a definite and foreordained result. This, 
for man, was happiness; and for all the other expressions 
or manifestations of matter, such as plants, animals, and 
all phases of inorganic nature from rocks to planets and 
stars, was perfect adaptation to environment. Change was 
everywhere in progress; had been from the beginning, and 
would continue until the end planned had been attained. 
This process of slow alteration advanced step by step 
through potentiality to actuality, never ceasing its march. 
For chance, or free will, which Empedocles regarded as the 
cause of changes, Aristotle substituted a potentiality in 
two directions—for good and for evil—maintaining that 
the choice of either resulted in the habit of either, culmi- 
nating in the two extremest of self-indulgence and asceti- 
eism, both of which were abnormal, reprehensible and un- 
fortunate, while virtue was a middle course between the 
two, that is, temperance in all things. As for the funda- 
mental cause of the continual changes in progress every- 
where, in both the animate and inanimate worlds, he con- 
tended that it must be found in the perpetual contest be- 
tween the inherent, invisible and unknown potentialities 
for good and evil. 

The ancients had no collection of demonstrated facts 
upon which to base their reasonings, such as the scientists 
of the present time possess. It is therefore not difficult 


Ancient Times 17 


to understand the very diverse conclusions reached by their 
philosophers in their search for Truth. These have no 
value at the present day beyond their literary merit, and 
the evidence they give of the gropings of the human mind 
in the darkness that then surrounded it. But for nearly 
two thousand years those of Aristotle were controlling in- 
fluences in the drama of humanity. 


THEOPHRASTUS (370-286 B.c.) 


BOTANY 


THEOPHRASTUS was born at Eresus, on the island of Les- 
bos, in the Aegean sea, and was of Greek parentage. He 
studied at Athens, at first under Plato, and then in the 
Aristotlean school, which was called—perhaps in a spirit 
of levity—the Peripatetics, because, during its lectures, it 
was the habit of its master to walk around the court, and 
in the gardens adjoining it, his pupils surrounding and 
folowing him. At the death of Aristotle, Theophrastus 
was elected its chief. In purely philosophical matters he 
followed the teachings of the departed leader; but, having 
himself decided inclinations to natural history in its bo- 
tanical aspect, he emphasized that science in his lectures 
until the school slowly came to be regarded as a collecting 
center, to which specimens from the world of vegetation 
were brought for investigation, classification and deter- 
mination of character. 

Unlike the herbalist Dioscorides, whose interest in plants 
was confined to the uses to which they could be put in the 
practice of medicine, Theophrastus sought to discover their 
relationship to each other, and was but slightly interested 
in their virtues. His first step was to separate them into 
the three broad categories of trees, shrubs and herbs, a 
classification which continued supreme from his day until 
near the close of the 17th century, when the better system 
of Linnaeus superseded it. Theophrastus is thus very 
properly regarded as the founder of the science of botany, 
for before him no one had attempted an organization of 
the members of the vegetable world. 


18 Beacon Lights of Science 


Lacking the enormous aid which even the crude micro- 
scope of the day of Linnaeus afforded in the study of 
plants, the discoveries made and recorded by Theophrastus 
are remarkable. They appear in his writings mainly as 
isolated statement, which must have been obtained in 
dissection and analysis by unaided vision. And while his 
system was crude, being based only on the external feature 
of comparative size, and was only carried a few steps 
further by the subdivision of these three major orders, it 
was a beginning in the process of organization which at 
once differentiated his work from that of the herbalists. 

Two of his literary products have come down to us in 
complete condition. One, entitled ‘‘ History of Plants,’’ is 
in nine books. The other, called ‘‘Theoretical Botany’’ 
is in six books. Besides these, he wrote essays on Min- 
erals, on The Physical Senses, on Fire, on Metaphysics and 
on several other subjects of minor importance. But of 
them only fragmentary remains are extant. A volume of 
his sketches has been preserved almost intact. In 1592 a 
complete edition of all his known writings was published | 
in Leyden, and in 1818 and 1866 in Leipsic and Paris. 
The first is most famous and useful, because accompanied 
by commentaries. It is a remarkable fact that in its pages 
are to be found many accurate descriptions of details in 
plant anatomy, which were rediscovered by modern botan- 
ists only with the aid of the microscope. 


ERASISTRATUS (335-265 B.c.) 


ANATOMY 


THE Greek physician and anatomist, Erasistratus, was 
born on the island of Cos in the Aegean archipelago. The 
actual dates of his birth and death are unknown. But in 
294 B.c., when presumably in his prime, he was employed 
as personal physician to Selucis Nikator, King of Syria. 
Subsequently he abondoned the active practice of his pro- 
fession, and devoted himself exclusively to the study of 
anatomy, where he made a number of important discov- 


Ancient Times 19 


eries. He seems to have been the first to comprehend and 
define the difference between the sensory and motor nerves 
of the body, and to trace both to their source in the brain, 
though there is nothing in what remains of his writings 
to indicate that he conceived the latter to be the seat of 
the mind. He also made a close approach to a correct un- 
derstanding of the functions of the heart, and the duties 
of the veins and arteries which lead from it to all parts 
of the body, but did not appear to have comprehended the 
work of the blood which circulated in them. He was a 
voluminous writer, but only a few fragments of his trea- 
tises have been preserved. Perhaps, if more had come 
down to us it might appear that he preceded Galen nearly 
five hundred, and Harvey nearly two thousand years in the 
discoveries for which they have the credit. 

So great was his reputation while living that, after his 
death, a School or Society of physicians and surgeons was 
organized who called themselves Erasistrateans, and who 
professed to practice and teach the physiological and ana- 
tomical principles for which he stood. But it did not last 
long, and there are indications that many of its members 
were practitioners of an inferior order, if not what we 
would now class as quacks, who merely joined to obtain 
the advantage in reputation which would be thought to 
attach to real pupils of a great master. 


EUCLID (circa 300 B.c.) 


MATHEMATICS 


LitTLE is known of the ancient and famous mathema- 
tician, Euclid, beyond the fact that he was a Greek by 
birth, was living and teaching in Alexandria during 
the reign of the first Ptolemy (323-285 B.c) and was the 
most renowned writer of his day on his subjects. His 
extant works that are considered his own beyond question 
are: ‘‘The Elements,’’ ‘‘The Data,’’ ‘‘The Phenomena,’’ 
‘‘The Opties,’’ ‘‘The Reflections,’’ ‘‘The Divisions of the 
Seale,’’ and ‘‘De Divisionibus.’’ It is thought that he 


20 Beacon Lights of Science 


wrote several—perhaps many—others, which have been 
lost. 

Of this list the first mentioned is the one that has im- 
mortalized him. It was in thirteen parts. Its reputation 
was so great that it was translated into Arabie under 
Haroun al Rashid (Aaron the Just), the renowned caliph 
of Bagdad (A.p. 786-809), and again under his son, Al 
Mamun. The latter version was rendered into Latin about 
A.D. 1120, and printed in Venice in 1482. 

It is now more than twenty-two centuries since Euclid 
worked out his famous propositions in plane and solid 
geometry and trigonometry, yet today they are taught in 
our schools with but slight modifications. In the develop- 
ment of the sciences, mathematics is the first step. With- 
out it, the second, mechanics, cannot be taught, nor can the 
third, astronomy, advance beyond the stage of observation. 
A Euclid was necessary before man could do much more 
than take notes and speculate on the phenomena of nature. 
It is true that there were mathematicians of sorts before 
his day, but he is rightly considered the father of that 
science. All of his propositions but two remain undis- 
puted, and these two (which will be found under the chap- 
ter devoted to Lobatchevski) are still correct for plane 
surfaces, but not for curved ones. 

The city of Alexandria where he taught, was founded 
by Alexander the Great in the year 332 B.c., and was there- 
fore in its first youth in his time. It was laid out by the 
architect Dinocrates of Rhodes on mathematical lines, in 
the shape of a parallelogram, its streets crossing each other 
at right angles. Egyptians, Greeks and Jews were the 
principal elements of its population, the proportion of each 
being in the order given, the Greeks constituting the in- 
tellectual, the Jews the commercial, and the Egyptians the 
laboring classes. Under the dynasty of the Ptolemies it 
flourished amazingly, and rapidly became the foremost 
city of the ancient world both in commerce and culture. 
To it the scholars and students of all the civilized nations 
of the time flocked, the former to teach and the latter to 
learn. Euclid, as one of the first class, established his 


Ancient Times 91 


school in an inconspicuous locality, where it at once became 
so famous that the king (Ptolemy I, surnamed Soter, The 
Preserver), provided a special auditorium for his use, and 
conferred on him every privilege and honor that could be 
desired. His classes were taught in Greek. The desire to 
attend them was so great that language schools were imme- 
diately established in the city, where the Egyptians, Arabs, 
Hindus, Persians, and other non-Hellenic people could ac- 
quire the classic tongue of the time. 


ARCHIMEDES (287-212 3.c.) 


MECHANICS 


ARCHIMEDES, who bears one of the most distinguished 
names among the ancients, was born at Syracuse in Sicily, 
at a time when that part of the island was still a colony 
of Greece, and under the rule of King Hiero II. As for 
several centuries it had been alternately in the possession 
of Greece and Phoenecia, it is possible that his ancestry was 
more or less of a mixture of the two races. His education 
was obtained at Alexandria, in Egypt, which was then a 
Greek colony under Ptolemy III, and ranked as the most 
famous center of learning in the world. 

His achievements indicate the possession of a gifted 
mathematical mind, coupled with the imagination of the 
natural inventor. He was a brilliant geometer, ranking 
in his time next to Euclid. He explained the principle of 
the lever, which indeed, as a mechanical contrivance, had 
been employed since remote antiquity; but so far as the 
records go, had not previously been mathematically investi- 
gated. Concerning its powers he is supposed to have said: 
‘Give me a place where I can stand, and a fulerum, and 
I will move the earth.’’ He also was the discoverer—or 
at least the first known employer—of the principle that 
‘‘the weights of bodies are proportional to their masses,’’ 
in which the word mass means ‘‘quantity of matter’’ and 
not volume. According to the story, the king had ordered 
a new crown, and had furnished the artificer with a definite 
weight of pure gold for its manufacture. When the article 


29 Beacon Lights of Science 


was delivered there was a suspicion that silver or even a 
base metal had been substituted to some extent for the 
precious one, and the matter was referred to Archimedes 
for investigation. As the geometer was stepping into his 
bath one day while the problem was under study in his 
mind, he was struck by the amount of water displaced by 
his body and spilled over the edge of the tub. At once 
he saw the solution of the problem. In his excitement he 
ran through the streets to his home entirely naked, and 
shouting ‘‘Kureka!’’ (I have found it). 

To Archimedes was due the development of that depart- 
ment of geometry called ‘‘Conic Sections,’’ treating of the 
circle, ellipse, parabola and hyperbola, all of which had 
of course been recognized before his time, but whose prop- 
erties had not been mathematically studied. He was a 
voluminous writer for his day. Of his works that are 
extant, three are devoted to plane geometry, three to solid 
geometry, one to arithmetic and three to mechanics. Like 
all the earlier mathematicians he tried to square the circle, 
and as the result of his calculations announced that the 
value of «+ was somewhere between the figures 3.1408169 
and 3.1428571, thus admitting in the end the insolubility 
of the problem, but indicating closely the ratio between 
diameter and circumference now employed. On the other 
hand, he succeeded in demonstrating that the area of a 
segment of a parabola is two-thirds that of the enclosing 
parallelogram, which was the first instance on record of 
the quadrature of a curvilinear surface. In his ‘‘Method 
of Exhaustion’’ he made an approach to the modern study 
of the Calculus. 

He was killed during the sack of Syracuse by the Romans 
under Marcellus. When that famous commander learned 
of his death he expressed great regret, and ordered a monu- 
ment to be erected to his memory. On it was engraved in 
stone a sphere inscribed in a cylinder. The great Roman 
statesman, Cicero, who was appointed governor of Sicily 
in 76 B.c., made a visit to this tomb, and gives a descrip- 
tion of it in his ‘‘Tuscan Disputations.’’ Its location at 
the present time is unknown. 


Ancient Times 93 


ERATOSTHENES (276-196 B.c.) 


ASTRONOMY 


ERATOSTHENES was born at Cyrene on the north coast 
of Africa, in the ancient Greek province or colony called 
Cyrenica, the region now known as Barea. He was of 
pure Grecian ancestry, and was given an excellent educa- 
tion under the noted instructor Callimachus, who later 
became the chief at the Alexandrian library. Upon attain- 
ing manhood Eratosthenes went to Athens, and later to 
Alexandria, where he served under his old master; and 
finally in 240 B.c., succeeded him at his death. There he 
remained during the balance of his long life until, at the 
age of eighty or thereabouts, having become totally blind, 
he died of voluntary starvation. While in his prime he 
was a writer of note. Of his essays many fragments are 
extant, which indicate that his culture was an unusually 
broad one. He disliked to be called a philosopher, prefer- 
ring the title of philologist (a lover of learning). He 
wrote on poetry, geography, mythology, anatomy, philoso- 
phy and literature in general. 

In science he is remembered as the first to make an esti- 
mate of the size of the world, on the assumption that its 
shape was that of a perfect sphere; and also among the 
first to calculate the angle which its equator makes with 
the ecliptic, the plane of its orbit in its annual journey 
around the sun, a measurement which is technically called 
at the present day the ‘‘obliquity of the Ecliptie.’’ 

In regard to the first of these: having ascertained that 
at midsummer in the city of Syene on the upper Nile— 
now the modern city of Assuan—which is located at about 
latitude 24° North, the sun shone at the bottom of a deep 
well there, he properly concluded that at the moment its 
* position must be vertically overhead, or in the zenith. On 
the same day he measured the altitude of the sun at the 
eity of Alexandria, whose latitude is approximately 31° 
North. He found the altitude to be a little over seven de- 
grees from verticality. Between Syene and Alexandria 


24 Beacon Laghts of Science 


(which are nearly on the same meridian) the distance was 
regarded as about 5000 stadia. The are of a circle sub- 
tended by an angle of seven degrees being approximately 
one-fiftieth of a circle, he concluded that the circumference 
would be fifty times five thousand, or 250,000 stadia. Un- 
fortunately, the exact length of the Greek stadium is un- 
known. It was the length of the national straight-away 
race course, and was always the equivalent of 600 Greek 
feet, which, if of the same length as the Latin foot, would 
be 0.2957 meter, or say 1114 inches, making the stadium 
177.42 meters or 586.3 feet. But the Greek foot was itself 
a variable measure. However, calling the stadium 600 
modern feet, or about one-ninth of a standard mile, the 
result reached by Eratosthenes would be 27,700 miles, 
which is so close an approximation to the true figure of 
the polar circumference (24,806 miles) as to make the per- 
formance a most ereditable one for the time, if we consider 
the crude instruments then available for measuring celes- 
tial altitudes, and the fact that the distance between the 
two cities was probably ascertained by pacing, and there- 
fore certain to be quite inaccurate. 

In the matter of the obliquity of the ecliptic he came 
much closer in his result, for his figure of 23° 51’ 19.5” 
differed but little from accuracy. At the present time the 
angle is 23° 45’. As this angle, in consequence of the pre- 
cession of the equinoxes, has been diminishing at the rate 
of about 50” per century since Eratosthenes made his esti- 
mate, the true figure for the angle at his time would have 
been 23° 62’ 20”. 


ARISTARCHUS (cirea 265 B.c.) 


ASTRONOMY 


THE native place of Aristarchus was at Samos, on the 
island of Cephalonia off the western coast of Greece. He 
is distinguished as having made the first recorded attempt 
to ascertain the comparative distances of the sun and the 
moon from the earth, by geometrical means. Nothing else 


Ancient Times 26 


is known of his history, and all his writings have been 
lost except a short essay describing his solution of this 
problem. In his day the earth was regarded as fixed and 
immovable in space, while the sun, moon, planets and stars 
moved around it. But to him it seemed more reasonable 
that the earth was a satellite of the sun, and the phenomena 
of eclipses—which he seemed to have thoroughly under- 
stood—confirmed him in this belief, for at their oceur- 
rences it was evident that the shadows cast by the earth on 
the moon, and by the moon on the sun, indicated clearly 
the relative distance of each. He therefore reverted to 
the older theory, according to which the earth was not 
stationary but revolved daily on its axis, insisting that 
the central fire postulated by Pythagoras was a myth, and 
that the sun did not shine by reflected light, but was itself 
luminous and, in fact, the source of all light coming to 
the earth, not only directly, but by reflection from the 
moon, the planets and the stars. 

Acting on this theory he reasoned that when the moon’s 
phase was in its first or third quarter, at which times it 
showed itself as a half sphere, the position which the three 
bodies occupied with respect to each other must be those 
at the vertices of a right-angled triangle, the moon being 
at the right angle of 90°, the sun at the most acute of the 
other two, and the earth at the least acute. He then at- 
tempted to measure with such instrumental assistance as 
was available in his day, the amount of the angle between 
the sun and the moon at the earth, at the half-moon stage 
of the satellite, and after repeated observations concluded 
that it was in the close vicinity of 83°. As the sum of the 
angles of a plane triangle are invariably 180°, and as the 
angle at the position of the moon was, by assumption, 90°, 
that at the sun must be the difference between 83° and 
90°, or 7°. Having then the three angles of the triangle, 
it was a simple geometrical problem to calculate the rela- 
tive length of the line extending from the earth to the 
moon as compared with that extending from the earth to 
the sun, namely as one to twenty. 

In theory Aristarchus was absolutely correct. But in his 


26 Beacon Lights of Scrence 


day no instrument for measuring angles accurately between 
bodies at great distances from each other was in existence. 
Moreover, and for the same reason, it was not possible then 
to determine exactly the half-moon stage. His data there- 
fore were in error, and hence his conclusion. It is now 
known that the angle at the earth between the moon and 
the sun, at the half phase of the former, is only a fraction 
of a minute less than 90°, instead of 83°. In consequence, 
the comparative length of the two distances from the earth 
to the moon, and from the earth to the sun, is as one to 
four hundred in place of one to twenty. 

His essay on this subject was published in Latin at 
Venice in 1498, and at Oxford in 1688 in the original 
Greek text. 


APGLLONIUS (cirea (225 B.c.) 


MATHEMATICS 


APOLLONIUS was a native of the city of Pergamos, in 
Asia Minor. The date of his birth is unknown, and prac- 
tically nothing of his personal history has come down to 
us except that he was the author of a treatise on the conic 
sections, which was so highly regarded in his time and for 
many centuries afterwards, that nearly the entire work of 
eight books was translated into Arabic, and later the fifth 
and seventh into Latin. 

The conie sections are those curves produced at the in- 
tersection of a plane with an upright cone. If the latter 
is cut horizontally and at any point of its height, the curve 
resulting is a circle. If the intersection occurs at any 
angle below horizontal and above parallelism to the slope 
of the sides of the cone, the curve is an ellipse. These two 
are closed curves, as they return to themselves. If now 
the plane intersects the cone at an angle parallel to the 
slope of its sides, a parabola is produced; and finally, if 
the intersection is parallel to the vertical axis of the cone 
the resulting curve is the hyperbola. These two are open 
curves, not returning to themselves. All four were first 


Anctent Times Q7 


described by a Greek geometer by the name of Menaechmus 
who lived at some time during the fourth century B.c. and 
about whom nothing is known beyond this fact. 

They greatly interested the mathematicians of the day 
and many of their properties became known. Especially 
in the case of the ellipse, which Apollonius aptly described 
as the curve with two centers. When Kepler showed that 
the planets revolved around the sun in ellipses, and Halley 
that the periodic or returning comets did also, that curve 
became of greater interest than ever to astronomers. To 
the layman the properties of the parabola are perhaps most 
attractive. It might be called a curve of one center, though 
better described as a curve of one focus. If, for ihdeatioe, 
a mirror is so constructed that all its axial sections are 
parabolas, and a beam of light is cast into it, all the rays 
will be reflected to the one point which is its focus. Or, 
conversely, if a source of light is set at the focus, all of it 
will be reflected outward in a beam whose rays are parallel 
to each other. This property is employed in the construc- 
tion of searchlights and lighthouse reflectors, producing 
a beam that penetrates a long distance before suffering dis- 
persion. Also, in a smaller way in locomotive and auto- 
mobile headlights. 


HIPPARCHUS (cirea 161-126 B.c.) 


ASTRONOMY 


THe Greek astronomer and mathematician, Hipparchus, 
was born at Nicaea in Bithynia, a political division of Asia 
Minor lying along the shores of the sea of Marmora and 
the Black sea. All his astronomical work, however, was 
done on the island of Rhodes. 

Of his personal history nothing is known. His writings 
also have been lost, but portions of them have come down 
to us through the works of Theon of Alexandria (circa 
A.D. 870), and of Ptolemy Philadelphus (A.p. 100-175). It 
is known that he wrote nine separate books, but of these 
only the ‘‘Commentary on Aratus’’ was reproduced com- 
plete by any subsequent writer. 


28 Beacon Lnghts of Science 


He is regarded as the founder of the science of trigo- 
nometry. He computed a table of chords, and is credited 
with a knowledge of the quadratic equation. He was the 
discover of the phenomenon known as the precession of the 
equinoxes, and is supposed to have been the inventor of 
the astrolabe, that instrument of the ancients with which 
they took the altitude of the heavenly bodies, and which 
was employed for that purpose in navigation until super- 
seded by the quadrant about 1730 and later the sextant. 
Hipparchus drew up a catologue of more than one thou- 
sand of the fixed stars. 

The ecliptic is the name given to the great circle round 
which the sun seems to travel from west to east in the 
course of the year. It was so called because the ancient 
astronomers quickly observed that eclipses happen only 
when the sun and moon are in or close to that circle. As 
is now well known, it is really the plane along which the 
earth actually moves in its annual journey around the 
sun. 

The plane of the earth’s equator, which divides it into 
the northern and southern hemispheres, if it be imagined 
as extended out into space, would not coimecide with that 
of the ecliptic. Instead, the angle between the two at the 
present time is about 2314 degrees, and is diminishing at 
the rate of about 50 seconds (or one-seventieth of a degree) 
per century; or say a degree in seventy centuries. If it 
kept on diminishing at that rate, in 1645 centuries 
the two planes would coincide. Fortunately this angle— 
which is ealled the obliquity of the ecliptic—has limits, 
which it does not and cannot pass. Astronomers calculate 
that it will reach its lowest possible amount of about 2214 
degrees in approximately 150 centuries from the present 
date, after which the motion will begin to reverse, and the 
angle between the two planes to increase until a maximum 
of nearly 25 degrees will be attained at the end of another 
330 centuries, or 480 centuries from the present time, when 
again a reverse movement will be inaugurated. 

Early in the history of astronomy it was observed that 
twice each year, namely, about the 21st of March and the 


Ancient Times 29 


23rd of September, the sun is vertically overhead at 
noon on the equator. These are called the equinoctial 
dates, and mark those places on the plane of the ecliptic 
where the plane of the equator, if extended sufficiently 
outward, would intersect it. These two points are not in- 
variable positions. Each year they move forward to the 
extent of about one-seventy-secondth part of a degree. As 
there are 360 degrees in a circle, it is plain that in about 
25,920 years they will have made a complete circle of the 
plane of the ecliptic. This phenomenon is called the pre- 
cession of the equinoxes. It is very remarkable that it was 
detected by this Greek astronomer over 2000 years ago, 
whose only observational instruments were the astrolabe, 
the gnomon and the polos. He was unable to explain its 
cause, which remained more or less of a mystery until 
Newton announced the laws that control the movements 
of the planets in space. 


DIOSCORIDES (cirea a.p. 64) 


BOTANY 


PEDANIOS D10ScoRIDES was a native of the Greek city of 
Anazarbus in Asia Minor. His profession was that of a 
physician. In his day that occupation did not include 
the practice of surgery, nor require a knowledge of anat- 
omy, though, in ease of light injury, or in emergencies, he 
was allowed to do what he could to relieve suffering. 

Of his early history, or of the degree of his educational 
equipment, nothing is known. He is first heard of as at- 
tached to the Roman army in his professional capacity, 
which took him to many parts of the known world of the 
day. Apparently he was a lover of nature, and used the 
opportunities his occupation provided to study vegetable 
life, and to make a remarkable collection of all the plants 
encountered which yielded, or were supposed to yield, 
medicinal virtues. These he listed and described in his 
monumental work entitled ‘‘De Materia Medica,’’ after 
physical disabilties and advancing years compelled him to 
abandon army life. 


30 Beacon Lights of Science 


So complete was this treatise that for fifteen centuries 
after his death it remained the standard work on the sub- 
ject. It was written in the Greek language, but while the 
author was still living a Latin translation was made; and 
later, from this, was rendered into most of the tongues of 
western Europe, as well as into Arabic, which was then 
the classical language of the East, as Latin was of the 
West. It was not until 1829, however, that it appeared in 
print, by which time naturally it possessed value mainly as 
one of the curiosities of ancient literature. 

Dioscorides was an observant man, and must have been 
as well educated for the duties of his occupation as could 
be expected for his time. But the knowledge of vegetable 
life that he gathered during his extensive journeyings was 
purely of the empirical kind, and in no sense scientific. 
While he discovered many plants of great value for their 
medicinal properties, and accurately described all that 
he collected, he made no attempts at classification, and was 
of course totally unaware of the chemical nature of the 
extracts and infusions he made from them, or why they 
produced the effects he observed. Nevertheless, his extra- 
ordinary industry in collecting, and his faithfulness in 
describing, as well as the methods he adopted for admin- 
istering his medicines, were of enormous service to man- 
kind during the Dark Ages, when science was non-existent, 
and superstition rampant. Even at the present time a 
few of his recipes are used in civilized countries, while 
most of them are rated as authoritative among the middle 
and lower class Turks and Arabs, and the people of 
North Africa. 


PTOLEMY (cirea a.p. 100-170) 


COSMOLOGY AND GEOGRAPHY 


CLAUDIUS PToLEMAEUS was a native of Upper Egypt, 
having been born in the vicinity of ancient Thebes. There 
are no records extant of his parentage or early life, but 
in the year a.p. 139 he was a personage of note in intellec- 


Ancient Times 31 


tual circles of Alexandria, and evidence that he was still 
living there in 161 is believed to exist. 

As a geographer, he appears to have been merely an 
editor or commentator on a work (which has been lost) on 
the subject by a Phoenecian navigator known as Marinus 
of Tyre, which must have been a production of consider- 
able importance. Ptolemy’s reproduction of it consisted 
of eight books. Five of these contain nothing but lists of 
place names which had evidently been visited by the orig- 
inal writer. In each case the latitude and longitude were 
given, together with a brief description of the locality and 
surroundings, of the people found there, of the productions 
of the vicinity, and such other items of information as 
might be gathered by the ordinary observant traveler. 
The other three—which perhaps were original with 
Ptolemy—were devoted to a description of the way to de- 
termine latitudes and longitudes; estimates of the size of 
the earth on the theory of its spherical shape, and a de- 
scription of his (Ptolemy’s) method of projecting points 
on a hemispherical surface upon a flat one, which he 
claimed was superior to those employed by either Eratos- 
thenes, Hipparchus or Marinus. From these notes of the 
actual navigator he constructed twenty-six maps of the 
known world of the day. These, for many centuries, were 
regarded as standard geographical authorities. 

In astronomy he originated the theory of the Cosmos 
which bears his name, and which was accepted as correct 
throughout Europe until the time of Copernicus and 
Kepler. This represented the Earth as immovably fixed 
in space, and as the center of the Universe, around which 
the sun, the moon, the five known planets and the stars, 
moved at uniform speed, carried by concentric transpar- 
ent spheres or shells, to each of which they were attached 
more or less immoyably. The first or innermost of these 
erystalline shells carried the moon. Beyond it in order 
came those bearing Mercury, Venus, the Sun, Mars, Jupi- 
ter and Saturn. In the eighth shell were all the fixed stars. 
To account for the alternate progression and recession of 
the planets, he originated his famous theory of epicycles. 


32 Beacon Lights of Science 


In this he claimed that the planets were not immovably — 
fixed in their respective shells, but that each one of them 
revolved in a circle of greater or less diameter, the center 
of which was immovably fixed on its particular shell. As 
to the Earth, he regarded it as the lowest and most stable 
of the elements of which matter in general was composed. 
Water, as exhibited in the ocean, and in lakes, rivers and 
rain, was the second element, and rested upon the first. 
Air was the third, being above these two, and fire the 
fourth. Beyond the last, and extending to the shell carry- 
ing the moon, was the blue sky, the vault of the heavens, 
to which he gave the name of the Ether. He appears to 
have made no efforts to explain the constitution or material 
of this last, nor to include it among his list of elements. 

Astronomers living shortly after Ptolemy’s day added 
in turn a ninth and tenth shell to the system. The first 
of these was to account for the phenomenon of the pre- 
cession of the equinoxes; and the second to explain more 
clearly the alternation of day and night. This was accom- 
plished by giving to it a daily circular motion from east — 
to west during which, by virtue of some mechanism all the 
others were carried with it. Still later, as the science of 
astronomy progressed, and new discoveries were made that 
could not be accounted for by the theory as originally out- 
lined, these were explained by its proponents by adding 
epicycle after epicycle to the scheme, until it became so 
complicated and so littered with these little circles as to 
draw from King Alphonso X of Castile—to whom it was 
being explained—the remark that ‘‘if he had been allowed 
to be present by the Deity when the Universe was being 
fashioned, he believed he could show him a better plan,”’ 
or words to that effect. By the time of Copernicus the 
whole theory was ready to fall to pieces by its own weight, 
though still adhered to by conservative minds, and even 
by such a brilliant observational astronomer as Tycho 
Brahe. 

To Ptolemy belongs the honor of having been the first 
to discover and describe that phenomenon called the moon’s 
‘‘eviction,’’ but its cause was unknown to him, and to all 


Ancient Times 33 


astronomers, until the day of La Place who, in 1786, com- 
pletely explained it. This is a perturbation or irregular- 
ity in the movement of the satellite due to the alternate 
increase and decrease in the eccentricity of the earth’s 
orbit. When this is at a maximum, it is capable of dis- 
placing the moon from its normal or average position in 
space sufficiently to alter the time of occurrences of lunar 
and solar eclipses as much as six hours. As eclipses are 
systematically recurrent phenomena, occurring in cycles 
of approximately eighteen years; and as this fact was well 
known (for the moon but not for the sun) to the ancients, 
whose astronomers were tireless observers of celestial hap- 
penings, and who prided themselves on their ability to 
predict eclipses, Ptolemy’s discovery was of much impor- 
tance, as it enabled them to increase the accuracy of their 
prophesies. 


GALEN (a.p. 130-201) 


ANATOMY 


CLADIUS GALENUS, as he was known in his time, ap- 
pears to have been a native of Mysia, an ancient province 
in the northwestern corner of Asia Minor, bordering on 
the Aegean and the Marmora seas, and was of Hellenic 
ancestry. During his youthful years he studied medicine, 
and such surgery as was known at the time, in Smyrna, 
Corinth, Alexandria and other large centers, and at the 
age of thirty received the appointment of physician to the 
school of gladiators at Pergamos. A few years later he 
moved to Rome, remaining there four years, during which 
time his reputation increased so greatly that he was offered 
the position of physician to the Emperor. Having re- 
turned to Mysia in his thirty-eighth year, he had hardly 
settled down to the practice of his profession, before he 
was summoned peremptorily by the emperors Aurelius and 
Lucius Verus, to attend them during a military expedition 
they were about to make, and obeyed at once. But on 
arrival at the camp of the army he found that a pestilence 


34 Beacon Laghts of Science 


had broken out there, and that the emperors had started 
on the return journey to Rome, whither he followed them. 
Little else is known of his movements, but it is generally 
believed that his death occurred in his 70th or 71st year, 
and that at the time he was in Sicily. 

Galen was a student and a voluminous writer. There 
are still in existence 83 documents of his that are known 
to be genuine, besides more than 400 others, the authen- 
ticity of which is questionable, but which are preserved 
for what they may be wortk in the collection of his writ- 
ings. Very few of them have any value beyond that of 
ancient curiosities, for in his time, and for centuries after 
it, the medical art was in no sense a science. But Galen 
was also an anatomist of unusual ability and brillianey for 
his day, and made one memorable discovery for which he 
has won immortal credit. This was, that the brain was the 
organ of thought. 

Up to his time various opinions had been held as to the 
organ in the human body which was the seat of the mind. 
For instance, the word brain, or any word that might be 
thought to refer to that organ, is not to be found in the 
Bible or in any ancient literature. Among the Babylon- 
ians the liver was regarded as the thought center. With 
the Hellenes the heart was considered the home of the soul, 
and the kidneys that of the mind, while sentiment and the 
emotions were supposed to reside in the bowels. ‘‘Bowels 
of compassion.’’ In Plato’s time the brain, though well 
known as a separate bodily organ, was regarded as an ex- 
tension, in the shape of a gland, of the marrow of the 
bones. And while he—for no reason that can be deduced 
from his writings—called it the seat of the soul, he exhib- 
ited no conception of it as the seat of thought. Aristotle 
later ridiculed the Platonic view (which certainly was 
nonsense), and said that the brain was simply a gland 
set at the top of the body, for the purpose of keeping the 
blood from acquiring too high a temperature, in other 
words, simply a cooling gland. It is true that one Ale- 
maeon, a Greek of Italian birth, who lived in the 6th 
century B.c., and who was recognized locally as a physician 


Ancient Times 35 


of ability for his time, had definitely taught that the brain 
was the seat of thought. But his opinion carried no weight 
with the philosophers, and was quickly forgotten. It re- 
quired a man of the experimental habits and international 
renown of Galen, to overthrow the childish speculation of 
his day on the subject. Accordingly, when, in about the 
year A.D. 160, he announced his discovery in a monograph 
entitled ‘‘De Anatomicis Administrationibus,’’ and elab- 
orated it inasecond one under the title of ‘‘De Usa Partium 
Corporis Humani,’’ his conclusions were at once accepted, 
and have never since been questioned. But many centur- 
ies elapsed before any further discovery of equal note oc- 
curred regarding the human body. In fact, not until 
Harvey, in 1628, published his work on the circulation of 
the blood, did man begin to know much about the temple 
in which his mind and personality made their dwelling 
place. 


DIOPHANTUS (cirea a.p, 250-350) 


MATHEMATICS 


DIOPHANTUS was a distinguished Greek mathematician, 
about whose personal history almost nothing is known, ex- 
cept that he lived and taught in Alexandria, Egypt. He 
is called the ‘‘Father of Algebra,’’ though that science is 
well known to have been developed to a considerable de- 
cree in India and Arabia centuries before his time. Of his 
three known works (‘‘On Arithmetie,’’ ‘‘On Polygonal 
Numbers’’ and ‘‘On Porisms’’) only six parts of the first 
mentioned are extant. These, however, display a remark- 
able grasp of algebra for the time, and fully warrant ac- 
cording to him the honor of having introduced the science 
to the European students of his day, and of having broad- 
ened its scope and capacity greatly. 

Algebra, the second department of the science of mathe- 
matics, derives its name from the title of a work by the 
Arabian philosopher Al-Khuwarasmi, who lived in the 
ninth century of the present era and was regarded as a 


36 Beacon Lights of Science 


noted mathematician. His professional life was spent 
mainly at Bagdad, where he worked in the astronomical 
observatory there, and wrote several treatises on that 
science. Among them was one entitled ‘‘Al-jabr wa’l 
mugabalah (Re-integration and Comparison) signifying an 
investigation which had to do with the methods by which 
equations may be reduced to integral forms. 

To exactly define the domain of algebra is not easy, for 
in one direction it shades into the higher departments of 
arithmetic, and in the other into the primary regions of 
the Caleulus. Comte’s definition is to the effect that while 
arithmetic is the calculus of values, algebra is the calculus 
of functions; the word calculus in both eases being in- 
tended to convey the idea of numbering or calculating, 
while function is used in the sense of a generalized quan- 
tity whose value at any given time depends upon the 
value of another quantity, also of a general kind. Thus, 
when it is said that the circumference or the area of a 
circle varies—in accordance with a fixed mathematical 
law—with the length of its diameter, both the circumfer- 
ence and the area are functions of the diameter. These 
functional relations when expressed in symbols are called 
equations. 

The oldest known written equation appears in a manu- 
script attributed to an Egyptian scribe by the name of 
Ahmes, who lived about 1700 B.c. He claimed to have 
copied it from another manuscript dating back some seven 
to eight centuries. It reads: 


‘‘The whole its seventh part, its whole, it makes 19.’’ 


Which, put in modern symbols would be o +a =19 


this being the form of the simple equation, and the prob- 
lem being to find the value of x, which is 16.625. In 
Kuclid’s day a knowledge of certain quadratic equations 
existed, but not until Diophantus does it appear that the 
science was taught in any organized way. In the century 
following his time the Hindu mathematician, Aryabhatta, 


Ancient Times 37 


made some important contributions to its growth, and from 
then until the writings of Al-Khuwarizmi appeared, no 
further progress seems to have been made. After him there 
was again a period of nearly seven hundred years until the 
Italian mathematicians, Tartaglia, Ferreo and others re- 
vived interest in it. Since then it has steadily advanced in 
capacity as a tool of science in all its departments. 


II 
THE MIDDLE AGES 


Historically, this period begins with the fall of the Roman Empire 
in the year A.D.. 476 and terminates at various dates between 1301 
(which is regarded as the beginning of the Renaissance) and 1517, 
when Luther inaugurated the era of the Reformation. But as this 
work deals only with the subject of science, it is considered best to 
end with the life of Copernicus, the outstanding figure of the 15th 
century. 

The notable historical events of this thousand years may be briefly 
summarized as follows. During the remainder of the 5th and most 
of the 6th centuries the Germanic or Teutonic people of central and 
northern Europe overran all of the European parts of the Roman 
empire, and towards the close of the 6th century the rise of the 
Arabian nationality began, which was destined during the following 
years to absorb all its Asiatic and African possessions. Through 
the 7th and 8th centuries, a process of fusion between conquerers 
and conquered was in progress, from which the latter emerged 
physically improved, and the former mentally, On the whole, the 
advantage remained with the conquered, and during the 9th and 10th 
centuries this was shown in the rise to supreme temporal power of 
the Roman church in Europe, and of Mohammedanism elsewhere. 
Towards the close of the 11th century, the two forces came into 
conflict with each other, in the episodes of the Crusades (1096-1272). 
These were inconclusive, but during their progress so much of new 
fact and new thought reached Europe, that its Dark Ages came to 
an end. With the opening of the 14th century, the learning of 
ancient Greece began to filter slowly back to Europe, and with that 
the modern era of Science may be said to have begun. 

In the Middle Ages, Italy was the commercial and intellectual 
center of the civilized world. Its schools and universities became 
so noted, that students flocked to them from the surrounding coun- 
tries. Yet the Italian race contributed only four men of marked 
scientific attainment to the period, while Arabia and Hindustan 
contributed five. However, the latter were merely bearers of ancient 
Greek knowledge, and since then these countries have added nothing 
to the accumulations of knowledge. 


ARYABHATTA (476-550) 


ASTRONOMY 


A Hrinpvu astronomer, who was born at Pataliputra in 
the upper valley of the Ganges river, Aryabhatta appears 
to have held in his writings—which were in the Sanscrit 
language and were translated into Arabic—that the earth 
had the form of a sphere, and revolved upon its axis. He 
also seems to have been the first to correctly account for 
the phenomena of solar and lunar eclipses, and conse- 
quently must have known and taught that the moon re- 
volved around the earth, and the latter around the sun. 
His advanced ideas of the cosmos, though totally unknown 
in Europe in his day and for many centuries afterwards, 
were accepted without question among the educated classes 
in India and Arabia, and probably in China, largely be- 
cause there was nothing to the contrary in the so-called 
sacred literature of these people, or for the reason that 
the literature of that kind among Oriental races was not 
regarded as inerrant in secular matters. A thousand years 
later, when the same beliefs were expressed by Copernicus, 
they were received with horror, because they were con- 
sidered to be in opposition to the teachings of the Chris- 
tian Scriptures. 

His only worlk that has come down to us is known as the 
Aryabhattiya. It was written in verse, and was divided 
into four parts entitled respectively ‘‘Celestial Har- 
monies,’’ ‘‘Elements of Calculation.’’ ‘‘On Time and its 
Measures’’ and ‘‘Spheres.’’ It was published in Sanscrit 
at Leyden, Holland, in 1874. <A translation into French 
of the second part was made in Paris in 1879. His writ- 
ings, and the views therein expressed, were held in high 
regard among the Arabs—to whom he was known as Arge- 

41 


42 Beacon Lights of Scrence 


hir, and exercised a strong influence on their conceptions 
of the external universe. 


BRAHMAGUPTA (598- ? ) 


MATHEMATICS 


BRAHMAGUPTA was the most prominent of Hindu mathe- 
maticians. Somewhere about the year 628 he completed 
the writing (in Sanscrit) of a work entitled ‘‘Brahma- 
Sphuta-Sidhanta (The Improved System of Brahma), of 
which Chapters XII and XVIII were on mathematics. 
These have been translated into English, and were pub- 
lished in London in 1817. In them he gives evidence of 
a fair acquaintance with certain fundamentals of the sci- 
ence, such as arithmetical progression, methods of obtain- 
ing the areas of triangles, quadrilaterals and circles, as well 
as the surfaces and volumes of cones and pyramids. He 
understood equations up to those of the fourth degree. 
His value for z (the ratio between the diameter and the 
circumference of a circle) was 3.16. He was the first 
known mathematician to use the so-called Arabic numerals 
which, in reality, originated with old Sanscrit alphabetical 
forms, being the first (or other) letters of the words one, 
two, three, etc., in that language. By some, Hector Boece 
(or Boethius) is credited—rather uncertainly—with their 
reduction to approximately their present form about the 
year 1500. By others, the change is attributed to Fibon- 
nacci (Leonardo of Pisa), who was in his prime early in 
the 18th century (1210-1220). What is important, how- 
ever, is, that with this almost forgotten Hindu, the idea 
seems to have originated to adopt symbols for the words 
of the numbers from one to nine, to add the zero symbol, 
and finally to give all position value, by which, without 
the use of any more symbols, any numerical quantity in 
whole numbers up to infinity could be expressed with ease. 
‘As a conception it ranks in importance with the invention 
of the wheel in mechanics. 

To him is also attributed the first employment of the 


The Middle Ages 43 


common or vulgar fraction (1%, 5%, %o, ete.). In the early 
years of the 17th century (1612) Stevin began to employ 
the decimal form of the fraction, which, however, appears 
to have been originally conceived by the Hindu mathema- 
tician Bhaskara (cirea A.D. 1150). 

It seems certain that whatever of the science of mathe- 
matics existed in ancient times in India, owes its origin to 
the Greeks, who brought it there by travelers and traders, 
and when their armies under Alexander the Great invaded 
the country in 327 B.c. The Hindu made but little use of 
it as a tool. Yet its fundamentals survived there when 
Greece gave place to Rome; and when the southern and 
eastern portions of the Empire of the latter passed into 
the control of the Arabs under Mohammed and his suc- 
cessors. Then, through the latter, the Hindus passed such 
of it as they had not forgotten, slowly through the cen- 
turies of the Dark Ages back to Europe, and the most of 
it by way of the Spanish Moors. 


AL KHUWARISMI ( ? -8381) 


MATHEMATICS 


Asp ALLAH MOHAMMED IBN Musa of Khuwarism was 
born in Khiva, in the region to the east of the Caspian 
sea, a very ancient town situated on the banks of the 
river Daria which, rising on the northern slopes of the 
Hindo Koosh mountains flows northward and empties it- 
self into the Aral sea. By race he was an Arab, and con- 
sequently by religion a Mohammedan. During the eali- 
phate of Al Mamun (783-833) he came to Bagdad, then the 
eenter of the Arabian world, and was connected with its 
astronomical observatory, where he wrote several books on 
mathematics. Among these was one devoted to setting 
forth the Hindu system of mathematical and algebraic 
notation and methods. Others described their sun dial, 
their astrolabe—an instrument employed to take the alti- 
tude of the sun, their current system of chronology, and 
what was known by them of the science of geometry. Such 


44 Beacon Lights of Science 


of his writings on algebra as have been preserved were trans- 
lated first into Latin and from that language in 1831 into 
English. They exhibit a fairly complete knowledge among 
Hindu mathematicians of equations up to those of the 
fourth degree. 

This individual—of whose personal history very little 
is known—was one of those few Arabian scholars who, 
when scientific knowledge was almost non-existent among 
their own race and in Europe, undertook to preserve parts 
at least of what had been accumulated among the Hindu 
philosophers who flourished in India a millennium previ- 
ously, in the days of Greek intellectual supremacy. An- 
other of the same class was Al Kinde (9th century), who 
is known to have written over two hundred treatises during 
his lifetime on almost every subject about which anything 
was supposed to be known in his day. Of these unfortu- 
nately only a few on medicine and astrology are extant. 

In Al Khuwarismi’s time Bagdad was a city of nearly 
600,000 population, and both intellectually and commer- 
cially the center of Arabian nationality. Under the bril- 
liant but despotic reign of the caliph Harun al Rashid 
(766-809) and his son Al Mamun (783-833), it attained 
its greatest magnificence and importance as the principal 
city on the caravan route between Europe and India. 

The Arabs as a race have produced very few men of 
intellectuality through their entire history. Of their origin 
little is certainly known, except that they belonged to the 
Semitic race of people, whose primitive home was the 
Arabian peninsula. Their development began in the south, 
where, about 1500 B.c. a flourishing nationality known as 
the Himyarites existed. Previously to them (or possibly 
contemporaneously) were the semi-mythical Mineans; and 
succeeding them were the Sabeans, whose period continued 
well into the Christian Era. These latter, inhabiting the 
southern and western coasts of the peninsula, were an 
active maritime people, and for several centuries conducted 
a brisk trade between Egypt, Mesopotamia and India, and 
down the east African coast as far as the mouth of the 
Limpopo river. This nationality began to split up and 


The Middle Ages 45 


decline in importance in the 5th and 6th centuries. 
Throughout central and northern Arabia the country has 
never been occupied except by wandering tribes continu- 
ally at war with each other. But during the lifetime of 
Mohammed (A.D. 570-632) the race experienced a remark- 
able process of consolidation under the influence of the 
fanatical religion he inaugurated, and began a career of 
ecnquest which extended westward all through northern 
Africa and even into Spain, and in the other direction 
included the whole of Mesopotamia and Syria. When 
Alexandria in Egpyt fell under the attack of the caliph 
Omar in A.D. 641, the great library there was destroyed 
under his order, because, as he is reported to have said, 
‘‘whatever in it agrees with the Koran is superfluous, and 
whatever disagrees is worse, and deserves destruction.’’ 
For the knowledge that had been accumulated by the 
Greeks the Arabs apparently had a supreme contempt. 
But for that much less scientific culture that was of Hindu 
or even Chinese origin they had more regard. Of them- 
selves they produced almost nothing in the way of dis- 
covery. 


AL HAZEN (965-1039) 


MATHEMATICS 


Eu HASAN IBN EL HASAN IBN EL HArTAM ABu ALI was 
a native of the city of Basra in the lower valley of the 
Euphrates, who ranked in his day as a mathematician and 
physicist of high repute, and also as a voluminous writer 
on general philosophy. His commentaries on the literary 
works of Aristotle, Galen, Ptolemy and Euclid are particu- 
larly illuminating as to the teachings and lives of those 
men. The most of his literary life was spent in Cairo, 
Egypt, where, among other activities, he wrote a notable 
treatise on the subject of optics, which ranks as the fore- 
most production of his day in that department of science. 
In it he enunciated correctly many of the laws of the re- 
flection of light from plane, spherical and parabolic mir- 


46 Beacon Lights of Science 


rors, and also had much to say on the phenomenon of re- 
fraction. He is believed to have been the first physicist to 
note and discuss the magnification of images when viewed 
through crystals or glass cut into the form of lenses. 

From these studies he was led to the investigation of the 
human eye, which he examined anatomically, discovering 
the lens in it, and partially explaining its operation in 
the phenomenon of vision. He recognized the fact that 
the image formed on the retina must be an inverted one, 
and admitted his inability to account for its transforma- 
tion in the mind to a correct position. 


BHASKARA (1144- ? ) 


MATHEMATICS 


A Hinpv scientist, who was the sixth successor of Brah- 
magupta as chief of the College or Society of learned men 
which, during part of the Middle Ages, was maintained in 
India; and in whose care was what remained of the knowl- 
edge that had come to them from Greece in the days of its 
intellectual supremacy. He was known by his contempo- 
raries as Bhaskara Acharya (the Learned One), and was 
the author of a book entitled ‘‘Sidhanta-Ciromanti’’ (the 
Crowning of the System). Two chapters of this work were 
devoted to mathematics, a third to astronomical ideas, and 
the remainder to various religious and social subjects. In 
accordance with the Hindu custom the text was written 
in verse (blank) but, differing from the methods of his 
predecessors, Bhaskara added copious commentaries in 
prose. 

The Hindus as a people should not be confounded with 
the other inhabitants of the peninsula of Hindustan—pop- 
ularly called India. Their homeland was in the upper 
valleys of the Ganges and Indus rivers, a highland region 
bounded on the north by the vast. uplift of the Himalaya 
mountains, and on the south by the much lower Vindhaya 
range. Into these parts, which now are called the princi- 
palities of Kashmir, Agra, Oudh and Punjab, embracing 
an area nearly twice as large as that of the state of Texas, 


The Middle Ages AT 


an immigration of white-skinned Aryans from the north- 
west and west began about 2000 B.c. They found the 
country inhabited by a people of low civilization with very 
dark skins who have been called Dravidians by the eth- 
nologists, and whose origin and racial relationship is 
still an unsettled problem. These, so far as the males, 
the invaders drove before them, but absorbed the females; 
with the consequence that the resulting Hindu race—con- 
stituting the highest class of the natives of India—pos- 
sess the well-cut features and mental characteristics of the 
Aryans elsewhere, under the dark skin of the displaced 
aboriginals. ) 

Of the early history of this composite race very little 
is known. The first reliable date is that of the birth of 
Buddha (557 B.c.) A century or so later they began to 
come into contact with Greeks, and from them, either in 
the way of friendly intercourse, or as conquerors, absorbed 
whatever of science has ever existed among them. About 
100 B.c. the Scythians invaded the country from the north, 
and in the sixth century A.p., the Huns. Finally, during 
the reign of the Ghaznivides (1001-1185), an Arabian 
dynasty that had become established in Afghanistan, their 
country passed under the control of that race. 

It is possible therefore that Bhaskara was part Hindu 
and part Arab in ancestry, and it seems quite certain that 
whatever scientific knowledge he possessed was of the na- 
ture of a legacy from Brahmagupta and his society, plus 
what he may have acquired himself. From the Arabs he 
gathered nothing, for as a race they have never been in- 
vestigators or students. The fanaticism of their religion 
prevented any interest in science. But, unlike the same 
characteristic which prevailed among theologians in EKu- 
rope during the Middle Ages, they were tolerant of Hindu 
science, apparently regarding it as child’s play—which 
indeed the most of it was. This toleration permitted some 
of the old Greek learning to slowly filter back towards 
benighted Europe by way of the few Hindu-Arabians who, 
to the best of their ability, had kept the lamp of knowledge 
from total extinction. 


48 Beacon Lights of Science 


Bhaskara is thought to have been the first suggestor of 
the decimal system. He certainly began to substitute 
symbols for words in algebraic problems. He wrote on 
weights and measures, square and cube roots, the rule of 
three, the methods of computing the surfaces and volumes 
of the common solids. His arithmetic was still very cum- 
bersome; for instance, division was accomplished by a proc- 
ess of repeated subtractions. He also wrote on astronomy, 
reflecting phases of ancient Greek speculations on the 
subject. Nothing that he left defines clearly the conception 
of the nature of the universe that was current in his day 
among the few who observed and thought. 


ROGER BACON (1214-1294) 


SPECULATIVE PHILOSOPHY AND NATURAL SCIENCE 


Roger Bacon was born at Ilchester, England, of highly 
respected parentage, and at a period of history when 
science, as the term is now understood, did not exist; but 
was represented among those who were eagerly—if some- 
what blindly—groping for explanations of the mysteries 
of the universe under the name of alchemists and astrolo- 
gers. He was well educated at Oxford in the classics, and 
later took his degree as doctor of theology at Paris. Re- 
turning then to England, he became a monk of the Order 
of the Franciscans, a religious society of the Roman Catho- 
lic church founded in 1209 by Saint Francis of Assisi. 

To appraise properly the life and work of Bacon it is 
necessary to understand something of the principles of this 
Order, and of the objects for which it strove. In addition 
to the vows of poverty, chastity and obedience which its 
members took, its fundamental conception was that they 
should lead a life as completely comparable to that of 
Christ as existing circumstances would permit. A simple 
costume—that of a shepherd of the day—was adopted, the 
use of shoes and of horseback riding was prohibited, con- 
versation with women absolutely forbidden, and complete 
fasting required on all Fridays from sunrise to sunset, 


The Middle Ages 49 


coupled with limited abstinence between All Saint’s day 
(Hallowe’en) and Christmas, and between Epiphany 
(Jan. 6th) and Easter. Beyond these observances their 
duties were to preach the doctrines of Christ, and to devote 
their lives to the service of their fellowmen in sickness and 
mental distress. The order grew very rapidly in number, 
and in extent of Europe covered by its branches, as evi- 
denced by the fact that during the plague known as the 
Black Death, which ravaged that part of the world in the 
years between 1343 and 1851, no less than 124,000 Fran- 
ciscans fell victims to it, in their zeal for the care of the 
sick, and for spiritual ministration to the dying. 

As a voluntary member of such an organization, it may 
be inferred with confidence that Bacon was a kindly man of 
a deeply religious temperament. At the same time he was 
sifted with an inquiring disposition; and after joining the 
Order carried on studies and researches in alehemy and 
opties, wrote voluminously of his discoveries, and discussed 
them freely with his brother monks. These activities, in 
spite of the blameless life he led, aroused the jealousy and 
dislike of his associates to such a degree as to bring upon 
him the charge of dealing with the black art of magie. 
In consequence, in 1257, he was condemned by the General 
of the Order to imprisonment for ten years in Paris, and 
deprivation during that period not only of his books and 
instruments, but of writing material. 

Upon the accession of Clement IV to the papacy (1265), 
Bacon managed to communicate with him, and the pope, 
a man of rather liberal tendencies, invited him to submit 
his writings for consideration. This Bacon did, in the 
form of a manuscript which later became known as his 
‘‘Opus Majus.’’ It was of the nature of a summation of 
all the conclusions reached up to that time in his studies 
and investigations in science, philosophy and religion. 
Shortly after its receipt, and before he had time to read 
it, Clement died. But the fact that he had desired to 
examine it, and to give the writer a hearing on its merits, 
secured his release from confinement and from open perse- 
eution until 1278, when he was again imprisoned under 


50 Beacon Laghts of Science 


the sanction of the new pope (Nicholas III) for another 
decade, but this time allowed to continue his investigations 
and studies, and to write of them. At the end of this term 
he was given his liberty, and returned to England about 
1288 where, in 1292, he completed his book entitled ‘‘Com- 
pendium Studii Theologiae,’’ and shortly thereafter— 
probably in 1294—he died. 

Like Leonardo da Vinci (1452-1519) Bacon was a nat- 
ural genius, a man far ahead of his time. But unlike the 
former, he was unable to cut loose from the errors of his 
day. He was a firm believer in astrology and the ‘‘ philos- 
opher’s stone,’’ that mythical compound for which the 
_alehemists sought during the Dark Ages which, when 
found, was expected not only to be capable of transmuting 
the base into the precious metals, but of acting as a panacea 
for all of the diseases and miseries from which hu- 
manity suffered during that sad era of intellectual twi- 
light. Yet even with such handicaps, and the harsh treat- 
ment he suffered from his fellow Franciscans, his brilliant 
imagination remained unclouded, and his optimistic tem- 
perament undiscouraged. He was the first among Euro- 
peans since the days of Grecian intellectual supremacy 
who held and taught that correct knowledge of nature 
could only be acquired by observation and study of its 
phenomena. He was particularly interested in optics, held 
advanced views on the refraction of light, and gave a cor- 
rect explanation of the apparent increase in the size of the 
sun and moon when on the horizon. He is believed to have 
learned—through the reading of Arabian documents that 
had been translated into Latin—of the explosive nature of 
a compound of sulphur, saltpeter and charcoal (gunpow- 
der), and to have made and exploded some of it under cir- 
cumstances that convinced the superstitious that he was 
a practicer of the so-called Black Art, and in league with 
the Devil. He was fully acquainted with the nature of 
the error in the condition of the calendar of his time— 
which was about eight days behind accuracy—and in the 
year 1263 prepared a rectified one, a copy of which is pre- 
served in the library of the University of Oxford. It was 


The Middle Ages Bl 


not until 1582 that this error—which by then had 
amounted to ten full days—was corrected by order of 
Pope Gregory XIII, under the guidance of Clausius, the 
official mathematician of the Vatican at the time. 

A thorough believer in the orthodoxy of his day, he was 
also one so deeply impressed with the wonders of nature, 
and the possibilities of achievement by man when control 
of its forces was gained by knowledge of their laws, that 
at times he became prophetic in his writings. Perhaps the 
best example of this is the following extract from one of his 
later manuscripts: 

‘‘Wirst, by the figurations of art, there may be made in- 
struments of navigation without men to rowe them, as 
great ships to brooke the sea, with only one man to steere 
them, and they shall sayle far more swiftly than if they 
were full of men; also chariots that move with unspeak- 
able force, without any living creature to stirre them. 
Likewise, an instrument may be made to fly withall, if one 
sit in the midst of the instrument, and doe turn an engine, 
by which the wings, being artificially composed, may beat 
the ayre after the manner of a flying bird. . . . But physi- 
eall figurations are far more strange; for by that may be 
framed perspects and looking glasses, that one thing shall 
appeare to be many, as one man shall appear to be a 
whole army, and one sunne and one moone shall seem 
diverse. Also, perspects may be so framed, that things 
farre off shall seem most nigh unto us.’’ 

Because of his broad learning, and in disregard of the 
efforts of his brother monks to disparage his reputation, 
he was known to the general public of the day as ‘‘ Doctor 
Admirabilis’’ and held by them in high esteem for his 
kindly and unassuming manners. All his manuscripts 
were written in the Latin language, in which he was very 
proficient. Six of these were published in the years be- 
tween 1485 and 1614. In 1733 his ‘‘Opus Majus’’ was 
published, and in 1859 his ‘‘Opus Tertiam,’’ ‘‘Opus 
Minus’’ and ‘‘Compendium Philosophiae’’ together, under 
the title of ‘‘Opera Inedita.’’ 


52 Beacon Lights of Science 


PEUERBACH (1423-1461) 


MATHEMATICS 


GEORG VON PEUERBACH was born in the vieinity of 
Linz, Austria. He studied in Vienna, and afterwards 
traveled in Germany, France and Italy, delivering astro- 
nomical lectures in the large universities. In 1454 he be- 
came private astronomer to King Ladislas of Hungary, 
and later, professor of mathematics at the University of 
Vienna. 

His notable accomplishment was the production of a 
table of Sines, which prepared the way for decimal frac- 
tions, which came into use early in the 17th century. 

In the development of the science of mathematics the 
study of arithmetic and the properties of numbers was 
naturally the first step; plane geometry, or land measure- 
ment the second, and plane trigonometry or angle meas- 
urement the third. Hipparchus, the Greek (cirea 161-126 
B.C.) is regarded as the first trigonometer of note, though 
Euclid, in elucidating some of the properties of triangles, 
really was the leader in that direction. 

Sines are one of the properties of angles. If two straight 
lines are so drawn on a piece of paper that they unite, the 
space included between them at the point of union is an 
angle, which may be of any size up to 180°. When 
of less than 90° they are called acute; when exactly 90° 
they are known as right angles, and when greater 
than 90° as obtuse. In the following figure of several 
concentric circles, in which a triangle is inscribed (one 
of the angles of the latter coinciding with the center of 
the circles), those lines drawn perpendicularly to one of 
the sides of the triangle and extending to the several cir- 
eumferences, namely A-B, C-D, E-F, G-H, are called sines 
of the central angle of the triangle. 

It is plain therefore that any angle we may choose to 
experiment with up to one of 90°, may have as many sines 
as we may care to ascribe to it by inscribing around it any 
number of concentric circles at various distances apart. 


The Middle Ages 53 


But an observation of the diagram will also show that all 
of them will bear a definite relation to the distance from 
the foot of each to the center of the circle. If this dis- 
tance is, say 12 feet, the sine for an angle of 30° will have 
a length of 16 feet. If the distance is 96 feet the sine will 
be 128 feet; if 3072 feet the sine will measure 4096 feet. 

If then it is desired to know the height of any object, 
and we can measure the horizontal distance from any given 
point to its base, and the angle between the horizon and 
its summit, the sine of the angle at that distance will be 


the altitude desired. 
SER aay 


Peuerbach was the first mathematician to compute the 
sines for angles of all the degrees between 0° and 90°, 
and for a large number of distances. 





A 


MULLER (Regiomontanus) (1436-1476) 


MATHEMATICS 


JOHANNES MULLER—who became known later as Regio- 
montanus—was born in the vicinity of Konigsberg, Aus- 
tria, and was educated in Vienna under the famous teacher 
Peuerbach. Having become a fine Greek scholar, an enthusi- 
ast in the ancient literature of that country, and a lover of 
the science of mathematics, he collected numerous Hellenic 
manuscripts on that subject, and translated them into 
Latin; thus bringing to the attention of European scholars, 


54 Beacon Lights of Science 


at a time when a revival of learning in that part of the 
world was beginning, the best fruits of the days of Grecian 
intellectual primacy. Among them were those of Ptolemy 
Philadelphus, Apollonius Pergaeus, Archimedes, Hiero and 
Diophantus. 

Miiller became very eminent as a mathematician, and 
his principal work, entitled ‘‘ Algorithmus Demonstratus,’’ 
published in 1534, was among the first—if not actually the 
first—in which the present system of symbolic algebra was 
employed. 

In 1475 he was called to Rome by the pope (Sixtus IV) 
to undertake the revision of the calendar, but died in the 
following year, before the work had been completed. 

Some of the ancient calendars appear to have been based 
upon the movements of the moon, and resulted in the 
institution of months as periods of 29 to 30 days, each of 
its four phases in their turn giving origin to the weeks. 
This certainly was the system of the Chinese and ancient 
Peruvians, and seems to have answered their needs fairly 
well through many centuries. On the other hand, the 
Semitic people (Egyptians, Jews and Babylonians) based 
the week of seven days on the number of the movable 
celestial bodies then known to them, namely, the sun, moon, 
and the five planets, Mercury, Venus, Mars, Jupiter and 
Saturn. With the Babylonians every seventh day of the 
month (called Shabattu) was reckoned as a ‘‘mysterious”’ 
one, on which special care must be taken to placate the 
gods, or at least not to offend them. From this ancient 
superstitition undoubtedly came to the Hebrews the insti- 
tution of the Sabbath, and the conception of the sacredness 
of the number seven. These ideas passed on to the Chris- 
tian world in the establishment of Sunday, the first day 
of the modern week, instead of Saturday the last one, as 
the holy day. 

But it was quickly noted among all the observant people 
of the olden days that these weekly and monthly periods 
could not be brought into agreement with each other, nor 
with the changes of the seasons plainly characteristic 
everywhere of the yearly period. Various means were 


The Middle Ages 55 


adopted to harmonize the three. The Egyptians, estimat- 
ing the year at 365 days, had 12 months of 30 days each, 
with 5 days added to the last one. The Jews reckoned the 
year as composed of twelve lunar months of 29 to 30 days 
alternately and at every seventh year added a thirteenth 
to balance up the account. The ancient Greeks adhered 
rigidly to lunar months as primary time divisions, until 
Solon introduced the Hebrew system about 594 B.c. Some- 
what later the year was fixed by them as a period of 36514 
days, and to accommodate the lunar calendar to this, an 
extra month of 30 days was intercalated about three times 
in each eighth annual term. 

The Romans seem to have originally regarded the year 
as a period of 355 days, which they divided into 10 months. 
This naturally resulted in a confusion which became so 
pronounced in the time of Julius Caesar (46 B.c) that re- 
form was necessary, and the Julian calendar was estab- 
lished. By it the year was reckoned as of 36514, days, 
divided into the months as we have them now, and the 
institution of Leap Year, to correct the discrepancy that 
still remained. 

But as the year is actually a period of 365 days, 5 hours, 
48 minutes and 46 seconds; by the time of Regiomontanus 
the calendar was out of order to the extent of about ten 
days. As the feasts and fasts of the Catholic church are 
all based on the coming of the spring equinox, due actually 
with our present calendar, on March 21st, but then coming 
ou March 11th, something had to be done, and accordingly 
was done in the year 1582 when, by order of Pope Gregory 
XIII, advised by the astronomer Clavius (who took the 
place of Regiomontanus after his death), ten days were 
deducted from that year, by calling the 5th of October in 
it the 15th. As this over-corrected the matter, it was 
further provided that the century years (1600, 1700, 1800, 
ete.), though normally Leap Years, should not be counted 
as such, excepting every fourth century beginning with 
the year 2000. By this arrangement the difference between 
the civil and the natural year will amount to less than a 
day in 5000 years. 


56 Beacon Lights of Science 


LEONARDO DA VINCI (1452-1519) 


GENERAL SCIENCE 


THis remarkable man, who was a native of Tuscany, 
Italy, was the natural son of a Florentine notary and a 
peasant woman. In his youth Da Vinci was eared for 
by his paternal grandparents. As he grew towards man- 
hood he became an acknowledged and honored member of 
his father’s family, and was given the best education that 
the times could afford. Possessing naturally unusual 
physical power, charm and social graces, he responded 
eagerly to the efforts of his preceptors, becoming one of the 
most versatile and astonishing individuals of which history 
has preserved the records. At an early age he was deeply 
interested in nature and was known as an artist of note as 
well as an engineer of ability. Under his direction, and 
in accordance with his plans, the Martesana canal was con- 
structed. He took an important part in the designing and 
building of the beautiful cathedral of Milan, and of several 
other notable public and private structures in that city 
and elsewhere. He was a keen student of human and 
animal anatomy—notably that of the horse—and com- 
pleted the model of one 26 feet high, which would 
have been east in bronze but for the capture of Milan in 
1500 by the French, whose soldiery ruthlessly destroyed 
it. Asa painter, his ‘‘Last Supper’’ and his ‘‘ Mona Lisa’’ 
have immortalized him, though they were but two of the 
many beautiful paintings he executed. 

With these accomplishments was combined an astonish- 
ing insight of nature and science, which led him to record 
in writing, and to express among his intimates, views and 
opinions far in advance of his time. If these had been 
widely disseminated or published, they could scarcely 
have failed to have revolutionized the knowledge of his 
day. But, strangely enough, when coupled with his extra- 
ordinary natural gifts in all other directions, he was not 
only left handed, but wrote in a back-handed style, and 
from right to left on the page. In consequence, his script 


The Middle Ages 57 


was almost undecipherable, and it was not until three 
hundred years had elapsed after his death that his writings 
were put into print. Among the remarkable conclusions 
which these revealed that he had reached, may be men- 
tioned the following: He asserted the sphericity of the 
earth, its daily revolution on its axis and its annual journey 
around the sun. He scouted the possibility of perpetual 
motion, which many of the mechanically minded of the 
time were attempting to attain, just as the alchemists were 
searching for a method of transmuting the base into the 
frecious metals; asserting, as a reason for his contention, 
that ‘‘force is the cause of motion, and motion the cause 
of force,’’ a view that would be expressed differently at 
the present time, but which contains the germ of what is 
known now as the conservation of energy. 

Nearly a century before Harvey he had grasped the idea 
of the circulation of the blood, and described in part the 
work it performed in the body. He was the first to give 
the correct explanation of the partial illumination of the 
dark side of the moon, by reflected light from the earth, 
and to ascribe the tides to the gravitative action of that 
luminary, even going so far as to explain the high tides as 
the combined action of the sun and moon. He anticipated 
Galileo in discussing the mechanics of the lever, the wheel 
and the inclined plane, and the acceleration in the speed 
of falling bodies. He is considered the founder of the sci- 
ence of hydraulics, the probable inventor of the hydrom- 
eter, and proposed schemes for the canalization of rivers 
by dams and locks (slack water navigation) which are in 
use at the present time. One of his keenest remarks was, 
‘“Whoever appeals to Authority applies not his intellect, 
but his memory.’’ Even in the domain of geology he gave 
expression to views in connection with the significance of 
fossils, the cause of earthquakes and volcanic eruptions, 
and the rise and subsidence of land areas, that slept for 
more than three centuries before restatement by Hutton 
and Lyell. 

Yet with all his remarkable endowments of person and 
intellect, his influence on the advance of knowledge was 


58 Beacon Laghts of Scrence 


comparatively insignificant. This was mainly due to the 
fact that his writings remained so long unpublished, but 
also because his achievements in art and engineering were 
so splendid as to overshadow his expressed views on science, 
the most of which could not be squared with the religious 
orthodoxy of the time, and hence were lightly received. 
Unlike Galileo, he made no effort to push these upon the 
world of his day, and so did not rouse the antagonism of 
the Church. On the contrary, up to the time of his death 
in Cloux, he not only retained his high standing in social 
and intellectual circles, but was court painter to the king 
of France (Francis I) at a liberal salary, and held the 
respect and friendship of his contemporaries both official 
and personal. 


COPERNICUS (1473-1543) 


ASTRONOMY 


NIKOLAUS KOoPPERNIGK (or Kopernik), of Teutonic an- 
eestry, but’ born in the year 1473 in the little town of 
Thorn in Poland, became known as Copernicus when he 
attained eminence, according to the fashion of the day of 
Latinizing the names of learned men. Little is known of 
his ancestry, but as his father was a reputable citizen of 
Bohemia, and his mother a sister of the bishop of Erme- 
land—a provinee of East Prussia that was ceded to Poland 
in 1466—it may be assumed that they were substantial 
people of the upper middle class, whose men took to the 
professions of arms, medicine, law or church, as inclina- 
tion or opportunity afforded. His father died when the 
boy was ten years old, leaving him tothe care of his uncle, 
the bishop. 

In his early youth Nikolaus received what was then re- 
garded as an excellent education, namely, a thorough 
grounding in the Greek and Latin languages and litera- 
ture, and the fundamentals of mathematics. At the age 
of eighteen he was sent to the University of Cracow, the 
capital-of Poland, where, during three years he specialized 


The Middle Ages 59 


in the higher mathematics and such of-the sciences as were 
then taught. In his 22nd year he went to Italy to perfect 
himself in languages, law, medicine and astronomy in the 
schools of Padua and Bologna. A decided inclination 
towards the last of these led him, in 1500, to go to Rome, 
and place himself under John Miiller, who, at the time, 
and under the name of Regiomontanus, had been engaged 
by Pope Sixtus IV to revise the calendar. In recognition of 
the ability he exhibited, he was appointed in 1503 Profes- 
sor of Mathematics at the University of Ferrara, where his 
main duties were to expound the Ptolemaic system of astron- 
omy to his pupils. But after serving there for less than 
two years he resigned, returned to Thorn, took the exami- 
nation for holy orders, was ordained, and accepted the 
ecanonry of Frauenberg under the bishopric of his uncle. 
There he remained for the balance of his life, a period of 


- thirty-eight years, devoting his time in about equal parts 


to the duties of his office, to the gratuitous practice of the 
medical art among the poor of his parish, and to the study 
of astronomy. At the end of twenty-five years, being then 
08 years old, he had completed the Treatise which insured 
him fame. But shrinking from the controversies he felt 
it would cause, he deferred its publication for another 
twelve years, only then consenting to place it in the hands 
of the printer because he believed the end of his life was 
close at hand. And so it proved. For he died at the age 
of 70, a few hours after the first copy had been delivered 
to him. 

This work, entitled ‘‘De Orbium Cclestium Revolutioni- 
bus,’’ was dedicated to Pope Paul III. In it he set forth 
and maintained-with a great diffusion of argument, some 
of which at the present time would be lightly regarded, the 
four following main themes: 

1. That the earth was a sphere. Knowing nothing of the 
laws of gravitation as set forth a century and a half later 
by Newton, or those of motion as exemplified by the centrif- 
ugal and centripetal forces, Copernicus argued that the 
earth must be of such a shape, mainly because that was 
the one perfect solid, its surface without beginning and 


60 Beacon Lights of Science 


without end, and with all its parts in complete balance with 
each other. 

2. That its orbit, as well as those of all the other mem- 
bers then known of the solar system, were circles, with 
the sun at their center, and that their motion therein was 
everywhere uniform in speed. This, he maintained, must 
be the case, because the circle, being the one perfect plain 
figure, was the only one that could account for observed 
periodicity. And for a like reason he held that the rate 
of motion for each must be uniform. 

3. That the earth and the planets revolved on their axes. 
But again having no conception of the force of gravitation, 
he was unable to explain why the waters of the ocean and 
all loose bodies clung to them throughout their revolutions. 

4. That the stars were at immense and varying distances 
from us. 

On the foundation of these postulates, he explained the 
variation of the seasons, the movements of the planets, the 
phases of the moon, and the precession of the equinoxes. 
But his mathematical and observational equipment was 
not enough to enable him to do so with entire accuracy in 
all cases, and so, to account for some observed irregulari- 
ties, he was compelled to fall back at times on one or more 
of the epicycles of Ptolemy. 

Such in brief is one aspect of the life of a gentle, clean 
and unselfish man, of a thinker whose mind had grasped 
clearly certain verities, but was not always equal to the 
task of demonstrating them logically. His treatise, which 
is his monument, is therefore open to much criticism, but 
it should be considered in connection with the status of 
science of the time, and remembering that in his day all 
matters in nature calling for explanation must finally be 
squared with any and all statements in the Bible that 
directly or remotely: touched thegquestion at issue. If that 
was not possible, then the interpretation advanced must 
‘be considered erroneous, and subject to the condemnation 
of the Church. It seems certain that Copernicus had 
reached the conclusion that his elucidations of the observed 
celestial phenomena could not be so squared. 


The Middle Ages 61 


That he was a man of great modesty, is made clear by 
the fact that at the outset of his thesis he disclaimed origi- 
nality, by calling attention to that theory of the cosmos 
believed to have been taught by Pythagoras 2000 years 
previously, which held that the earth was a sphere revolv- 
ing around a central source of light and heat, as also the 
sun, the moon, the planets then known, and the stars; 
which source however was itself invisible, because towards 
it the under side of the earth was always turned. 

The place of Copernicus in history is that of the man 
who took the first step in medieval times in setting forth 
the idea that some kinds of knowledge may be acquired by 
other means than through the study of the Scriptures, the 
writings of the Fathers of the Church, and the philoso- 
phies of the Ancients. In doing this he fairly earned the 
title of the Father of Modern Science, regardless of the 
many errors he made in his exposition of the Universe. 
Being unquestionably a devout and humble-minded man, 
as well as an officer in his church, his delay in giving pub- 
licity to his views until he believed himself to be on the 
verge of the grave, where he would be beyond the reach of 
those who could eall on him to recant or suffer the conse- 
quences, may easily be understood, and condoned if 
thought necessary. We are not always required to pro- 
claim our views from the house top. His epitaph, which 
he prepared himself, was thoroughly characteristic of the 
man. 

‘‘T do not ask the pardon accorded to Paul. I do not 
hope for the grace given to Peter. I beg only the favor 
which you have granted to the thief on the eross.’’ 

His book was condemned as heretical by Martin Luther, 
a contemporary, and in 1616 it was placed in the Index 
Expurgatorius by the Church of Rome. 


62 Beacon Lights of Science 


FALLOPIUS (1490-1562) 


ANATOMY 


GABRIEL LE FALLOPIO was born in the country, in the 
vicinity of Modena, Italy. Nothing is known of the first 
half of his life, and even the date of his birth is uncertain, 
some historians placing it as late as 1523. This seems 
highly improbable, for on that basis he would have been 
only twenty-five years old when, in 1548, he was advanced 
from an assistant professorship in anatomy at the Uni- 
versity of Ferrara to the rank of a full professor at 
the University of Pisa, from which, in a few years, he 
was called to take the very important chair of anatomy at 
Padua made vacant by the departure of Vesalius, who had 
been compelled by the court of the Inquisition to resign, on 
account of certain of his teachings which were averred to 
be in conflict with the religious orthodoxy of the day. 

Fallopius was a writer on both anatomy and medicine, 
but his reputation rests almost wholly on the discoveries 
he made in certain of the organs of the human body, 
coupled with his exposition of their functions. These were 
of such importance as to place his name alongside of those 
of Vesalius, Eustacio and Fabricio as one of the four prin- 
cipal founders of the modern science of anatomy. 

He was the first to accurately describe those two im- 
portant bones—the ethmoid and sphenoid—which respec- 
tively form the outer and the inner frontal parts of the 
human skull, and which, combined with six others, enclose 
the brain. Through minute perforations in the former the 
delicate filaments of the olfactory nerves pass outward to 
their proper termination in the nose. In all animals where 
the sense of smell is especially acute, as with the dogs, the 
central part of this bone, which determines the division of 
the nostrils, is markedly developed. If it were not for this 
division, half of the area now occupied by the terminal 
buds of these nerves would not be available. The sphenoid, 
situated lower down towards the base of the skull, has 
roughly the shape of a moth at rest. Two of the wings 


The Middle Ages 63 


form part of the floor on which the brain rests, and other 
parts constitute the outer rim of the orbits of the eyes. 
To surfaces of this bone are attached the powerful muscles 
that actuate the jaws in mastication. This bone also is 
perforated to pass five sets of facial nerves, including 
those of taste. 

The canals through which the auditory nerves pass from 
the brain to the ear were discovered by him, and are known 
as the Fallopian aqueducts. Huis name is also preserved 
in the Fallopian tubes, whose function he demonstrated ; 
and to his studies of the intestines we owe the discovery 
of those circular folds lying in series along their inner 
wall, and projecting somewhat into them, that add to their 
absorptive and secretive capacity. A complete edition of 
his writings in four folio volumes was published in 1600. 


Miser bit ve ¥ ; 


OE hy 


| ce a i a ; pe 





Ill 
THE SIXTEENTH CENTURY 


With the beginning of the 16th century, Europe, which then meant 
the civilized world, had emerged from the gloom of the Dark Ages. 
The Renaissance was in full flower. 

However, the continual internecine wars greatly hampered the 
spread of learning. Beyond a few scattered colleges and the monas- 
teries, education was almost unknown. 

Despite the unfavorable soil, this century produced a small group 
of men of giant intellect who were to become pathfinders in their 
allotted fields. The work of the astronomer Copernicus was largely 
done in this century. Galileo discovered three of the moons of Jupiter. 
Kepler defined the laws of planetary motion. In physiology, Harvey 
discovered the circulation of the blood. In mathematics, Stevin 
introduced the decimal system, and Napier invented logarithms. 
There are only some dozen names all told in this century, but all 
are of high achievement. 


TARTAGLIA (1500-1557) 


MATHEMATICS 


NicoLo TARTAGLIA—whose real name, however, was 
Nicolo Fortuna—was born in the city of Brescia in north- 
ern Italy. Practically nothing is surely known of his par- 
entage, his early history or his educational equipment. 
That he possessed naturally high mathematical ability is 
clear, for he was a lecturer on the subject at the University 
of Verona, and later taught the science in Venice. He was 
also a writer on physics which was, at the time, beginning 
to emerge as a separate department of knowledge from its 
ancestry in mechanics, as various phenomena of motion, 
heat, etc., were subjected to preliminary mathematical 
analysis. His work on this subject, entitled ‘‘The New 
Science,’’ published in 1537, shows that he had discovered 
(or, at least investigated), the law of falling bodies, and 
had applied its principles to the flight of artillery projec- 
tiles. From another volume on mathematics published in 
1556, the degree of development of that science in Italy 
in his time can be fairly estimated. 

He is principally remembered, however, in connection 
with the subject of the cubic equation, which was the alge- 
braic conundrum of his time. According to general belief 
he discovered the method of its solution during the year 
1541 and, as the story goes, gave it, under a solemn prom- 
ise of secrecy, to one Girolamo Cardano, a fellow country- 
man and also a brilliant mathematician, but, in addition, 
a most disreputable and unscrupulous character. Cardano 
unhesitatingly violated the confidence reposed in him, and 
published the solution over his own name, and as his own 
discovery. In spite of the efforts Tartaglia made—even to 
the extent of carrying the question into the courts—Car- 


67 


68 Beacon Lights of Science 


dano succeeded so well in palming off the discovery as his 
own, that ever since it has been known in the books as 
‘‘Cardano’s Method,’’ though it has been conclusively 
shown that the credit rightly belongs to Tartaglia. It was 
perhaps the most important—and certainly the most inter- 
esting—mathematical accomplishment of the sixteenth 
century. 


VESALIUS (1514-1564) 


ANATOMY 


ANDREAS VESALIUS was a native of the city of Brussels 
in Belgium. After studying at the Universities of Louvain, 
Cologne, Montpelier and Paris he became a lecturer on 
surgery and anatomy at several of the large universities in 
Italy where medicine was taught; and while so serving was 
offered the position of chief physician to King Charles V 
of Spain, and took up his residence at Madrid. In 1564 
he was accused by envious enemies of having dissected a 
human body before life was extinct, and brought for trial 
before the officers of the Inquisition, who, though they did 
not hesitate themselves to torture heretics, condemned him 
to death. The King, however, secured the commutation of 
the sentence to one imposing a visit of expiation to the 
Holy Land. He made the outward trip safely, but on the 
return, the vessel in which he was traveling was wrecked 
on the rocky shore of Zante, an island off the west coast of 
Greece, and died there in consequence of exposure and in- 
juries received. 

Vesalius is regarded as the foremost of the anatomists of 
his time. He was a lecturer of unusual charm, and a writer 
of note in his specialty. He was the first to break away 
from the views held by the ancient Greeks as to the fune- 
tions of the various organs of the human body. 

Because of the lack of proper instruments for dissection, 
and of any such aid for the study of minute details as is 
at present available by the use of the microscope, com- 
paratively little real knowledge of the human body had 


The Sixteenth Century 69 


accumulated among the Greeks. Hipparchus (460-360 
B.C.) is generally credited with a fair knowledge of 
the skeleton. At Alexandria, when in its prime (150-200 
B.C.), it is known that dissection was practiced at the medi- 
cal schools there, but did not go much farther than to 
expose the principal vital organs and speculate on their 
duty. Galen (A.p. 1381-200) was the first to record with 
any degree of accuracy what he observed in his surgical 
work, but as his theories of the processes of digestion, and 
the work performed by the blood and the other bodily 
liquids, were almost entirely erroneous, the conclusions he 
passed on to his successors were of little real service in 
curing bodily ills. During the Dark Ages in Europe dis- 
section was considered an impiety, and was only practiced 
in secrecy and at great peril. Early in the 13th century 
conditions in this respect began to improve, to the extent 
that the bodies of criminals were generally granted to sur- 
geons for study. But even then, and through the three 
following centuries, clinics consisted of little more than 
the opening of the trunks of such subjects for the display 
of the organs contained, and explanation of their opera- 
tion according to ancient views. 

Vesalius advocated complete abandonment of these old 
conceptions. The result, as usual, was a storm of protest 
from those who clung to what was thought to be the supe- 
rior wisdom of the ancients. The contest increased in violence 
until the Church was appealed to as the final authority, and 
to its credit it should be recorded that in 1556, after con- 
sideration of the arguments advanced by both parties, it 
held that since a knowledge of anatomy is useful to man, 
dissection may be allowed. 

While in Palestine, and doing penance, Vesalius received 
and accepted an offer to occupy the chair of anatomy at 
the University of Padua in Italy, and was on his way there 
when shipwrecked. His writings, which were numerous 
and important, though containing many views since aban- 
doned, were collected and published in Leyden in 1725. 


70 Beacon Lights of Science 


GESNER (1516-1565) 


NATURAL HISTORY 


KONRAD VON GESNER was a native of the city of Zurich, 
in Switzerland, and was educated for the medical profes- 
sion at the University of Basle. Incidentally he was a fine 
classical scholar, and also well posted in such of the dis- 
coveries in physics as had been made up to his time. But 
his favorite subject was animal life, not so much in its 
purely scientific aspect, as in the way life of any kind 
appeals to the man of a kindly nature. In 1541, after 
several years of travel and study, in Strassburg, Bourges, 
Paris, Montpelier and other educational centers, he ac- 
cepted the position of professor of physics at the University 
of Zurich, and while fulfilling his duties as such began 
work on his ‘‘Historia Animalium.’’ It was written in 
Latin according to the custom of the time, and was in- 
tended to be a description of every kind of animal known 
at the time by himself, or of which he could obtain an 
account from others that seemed to be sufficiently reliable. 
As planned, it was in six parts or volumes, the first on 
animals that bring forth their young alive, the second on 
quadrupeds hatched from the egg, the third on birds, the 
fourth on aquatic life, the fifth on serpents and the sixth 
on insects. The first four of these were completed and 
published in the years between 1551 and 1558, but the 
last two, as also a work on plants, were unfinished at the 
time when, taken ill with the return of the plague known 
as the Black Death, his active life came to an end. 

In spite of the complete lack of technical knowledge of 
his subject, and his unscientific classification, Gesner ren- 
dered a real service to his generation in drawing the atten- 
tion of those who could read Latin to the interesting facts 
of life all around us; and his work, like that of Aldrovandi 
the Italian (1522-1605) on mollusks and birds, and the 
very similar volumes by Buffon (1707-1788), did much to 
stimulate an interest in natural history, which bore fruit 
of better quality when Linnaeus (1707-1778) made his 


OL 260d bmoIn7 SIIUAIIS fo CmapvrIp JDuU014WDN ©) 


EE BC pete 


ct Betis 


1a 


One, 





=f 


te 


iis 


é 


oe 


ne 
4 Wee 


~f 
it 


sg5EDNS i onl oS wall 


P oN 


HITTIN TITTY t UU 





RATT 


°y 


YHt chad? 
OF Tht F 
UMWERSITY OF SLLIMGIS 





The Sixteenth Century 71 


improved but still incorrect classification, and culminated 
with that of Cuvier (1769-1832), the first of the natural- 
ists to base his groupings on the firm foundation of com- 
parative anatomy. 

Gesner’s unfinished volumes were published some years 
after his death, in about the shape in which he left them. 


EUSTACIO ( ? -1574) 


ANATOMY 


BARTOLOMEO EustAcio was an Italian by birth. Of 
his native city, his parentage and his youth practically 
nothing is known. But in 1562 he was a teacher of his 
art—medicine and surgery—at the Collegio della Sapienza 
at Rome where, on account of his great ability as well as 
personal charm as a lecturer, he had attained a high repu- 
tation. His name, and those of Vesalius and Fal- 
lopius are linked together in the annals of science as 
the founders of the modern school of anatomy. Vesalius, 
a Belgian (1514-1564), was the first of whom records have 
been preserved since the days of Galen (130-201) to dis- 
sect the human body, and to make accurate drawings of 
his sections. Having been accused after one of these opera- 
tions of human vivisection, he was condemned by the Col- 
lege of the Inquisition to make a penitential journey to 
Jerusalem, and was lost through shipwreck on the return 
trip. Fallopius, an Italian (1490-1562), while lecturing 
at the Universities of Padua and Pisa in surgery, demon- 
strated the functions of the Fallopian tubes which conduct 
the human ovum to the uterus. 

Eustacio, the most prolific of the three in the matter of 
important anatomical findings, was the discoverer of the 
eustachian tubes which connect the nasal cavity with the 
inner ear; of the rudimentary valves in the heart (which 
also bear his name), and was the first to call attention to 
the chain of small bones in the ear—the malus (hammer), 
ineus (anvil) and stapes (stirrup), and to describe their 
several functions in the phenomenon of hearing. He also 


72 Beacon Lights of Science 


gave the earliest known accurate description of the thoracic 
duct, which connects the cavity of the chest in mammals 
with the abdominal cavity, and took a very prominent part 
in describing the development of the teeth, and also the 
structure and functions of the kidneys. 


FABRIZIO (1537-1619) 


ANATOMY 


THE birthplace of Girolamo Fabrizio was Aquapedente, 
in Italy. He was the son of peasants but, nevertheless, 
was given a good primary education, and early evinced so 
marked an interest in natural history that the opportunity 
was afforded to attend the classes in medicine and surgery 
at the University of Padua. So greatly did he distinguish 
himself in research, and afterwards as an assistant instruc- 
tor, that he ultimately rose to the position of professor of 
anatomy and surgery there and held it until incapacitated 
by old age. 

He was an expert in diseases of the eye, ear, larynx and 
intestines, and in the development of the human foetus. 
His greatest discovery was that of the valves in the veins. 
But strangely, while he called attention to these in his lec- 
tures, he did not understand their use, and it remained for 
Harvey in 1615 to show that they prevented the backward 
flow of the blood and so compelled it to move onward to- 
wards the heart which, in its turn, forced it into the lungs. 

In 1617 his great work, entitled ‘‘Opera Chirurgica,’’ 
was published, and went through seventeen editions before 
the demand for it ceased. So highly was he esteemed by 
his countrymen when in his prime, that the Venetian 
republic built for him an anatomical amphitheater, where 
his lectures could be attended by a large audience, paid 
him a salary of 1000 crowns, and made him a knight of 
the order of St. Mark. In accordance with the custom of 
the times his name was Latinized, so that he was known 
throughout the educated world as Fabricius. 

In the 16th and 17th centuries northern Italy was the 


The Sixteenth Century 73 


commercial and intellectual center of the world, and its 
educational institutions at Padua, Bologna, Genoa, Mo- 
dena, Parma, Pavia and Turin attracted students from all 
parts of Europe. Most of them originated in the 12th and 
13th centuries, as outgrowths of schools that had ex- 
isted prior to that date in connection with cathedrals and 
monasteries. In these only theology, medicine and ecclesi- 
astical law were taught, and the student was expected at 
the end of his studies either to take active service in the 
Church, or to assume the vows of one of the many monastic 
orders then in existence. In their later development de- 
partments of philosophy, logic, rhetoric and civil law were 
established, and became important, and their direct super- 
vision by the clergy was gradually abandoned. Finally 
the sciences in their then immature state, beginning with 
mathematics and astronomy, were introduced, and theology 
and church law relegated to seminaries connected with the 
monastic orders. In these medieval universities instruc- 
tion was wholly by lecture, attendance was optional and the 
degrees of bachelor and master of arts were conferred only 
on those—comparatively few in number—who, by reason 
of the exhibition of marked capacity, were selected first as 
assistant instructors, and later rose to professorships: In 
some of them, as was the case at Bologna, the students 
themselves constituted the corporation, and arranged for 
all the instructional activities. In the majority, however, 
the tutors and professors and assistant lecturers or demon- 
strators gradually combined to form the governing body. 
In both, the reputation of the organization, and the num- 
bers of students attracted, depended wholly on the stand- 
ing of the lecturers in their different specialties, and the 
rivalry and competition between them for the services of 
a brilliant and interesting speaker was often strenuous. 
Fabricius was one of the most noted of these professors. 
Yet he failed to realize the importance of his great ana- 
tomical discovery. 

The arteries, carrying freshly renewed blood from the 
lungs under the urge of the pumping heart, as they ad- 
vance towards the extremities of the body, continually 


74 Beacon Laghts of Science 


dividing and steadily decreasing in size, terminate finally 
at the extremities in the minute tubes called capillaries, 
which themselves connect there with equally small tubes 
leading into the veins. The latter, now continually enlarg- 
ing in section as joined by other veins, have the task of 
earrying the dark and impure blood back to the lungs for 
purification, but no longer can depend upon the heart for 
motive power. Here then nature has solved the problem by 
providing in many of them a system of valves at regular 
intervals of their length which, aided by a slight involun- 
tary contraction of the vein walls at regular intervals of 
time, forces the blood on to its proper destination. 


GILBERT (1540-1603) 


NATURAL SCIENCE 


WILLIAM GILBERT was a native of Colchester, England, 
where his father held a public office. He was educated at 
Cambridge, from which institution he received the degree 
of M.D. in 1569. In 1578 he opened an office in London, 
and rapidly acquired so high a reputation that he was 
appointed court physician, a position which he retained 
for the balance of his life. In 1600 he became president 
of the London College of Physicians. 

While making his living in the practice of his profes- 
sion, he devoted all his spare time to researches in physies, 
confining them largely to electrical and magnetic phe- 
nomena, where he made several discoveries of importance. 
The principal one with which his name is properly con- 
nected was the recognition of the fact that the earth was 
itself a great magnet, and that the movements of the mar- 
iner’s compass were due to that fact. He was the first 
student of the subject to use the term ‘‘electric foree,’’ and 
to point out that many substances besides amber could, by 
friction, be made to exhibit the presence of electricity on 
their surfaces. His treatise ‘‘De Magnetico,’’ was the earli- 
est publication of any importance in that branch of science. 
Naturally, some of the views and theories elaborated 


The Sixteenth Century 75 


therein have not since been realized, but a surprisingly 
large proportion have been, for he was a close and keen 
observer, as well as a conscientious recorder of phenomena 
witnessed. 

Columbus, the Navigator, is believed to have been the 
first to express the opinion that the compass does not point 
to the geographical pole, and that the magnetic pole to 
which it does point must be a movable location, because of 
the continual variations of the directions to which the 
magnet points. Norman, a London instrument maker, was 
the first to call attention to the dipping action of the instru- 
ment. To the astronomer, Halley, we owe the first mag- 
netic charts. Another London instrument maker, Graham, 
discovered the diurnal variations. Gauss, the mathema- 
ticlan, made an exhaustive study of terrestrial magnetism, 
and to Humboldt is due the suggestion of making syste- 
matic observations of the daily and annual variations at 
all available points on sea and land. 

The earth has a magnetic equator, where the needle, when 
freely suspended at its central point, remains in an abso- 
lutely horizontal position. This line is an irregular one, 
crossing and recrossing the geographical equator at many 
places, but never departing more than about a dozen miles 
from it. At all locations to the north of this wavy circle 
the south pole of the magnet not only points to the north 
magnetic pole, but dips towards it. South of it the needle 
points and dips to the south magnetic pole. 

These magnetic poles do not coincide with the geographi- 
cal poles. The northern one was discovered in 1831 by Sir 
James Clark Ross, on a peninsula called Boothia Felix 
projecting into the Arctie regions from the Canadian coast 
in latitude 70° N. and longitude 96° W., and hence is dis- 
tant about 1375 miles from the geographical pole. 

The south magnetic pole was discovered in 1842 by the 
same explorer. It lies on that part of the great Antarctic 
continent called Victoria Land at about latitude 73° S. and 
longitude 145° E., and is therefore about 1150 miles north 
of the geographical pole. In both cases it has since been 
discovered that these poles are not stationary localities, but 


76 Beacon Lights of Scvence 


wander irregularly from year to year within the limits of 
a circle of about 20 miles in diameter. In approaching the 
two localities the dip of the compass increases steadily and 
rapidly, and when the exact position for the time is reached, 
it assumes a vertical position. The cause of the wandering 
is ascribed to the continual slight changes in progress in 
the shape of the earth, each of which, to some extent, re- 
sults in more or less of a displacement of its center of 
gravity. 


BRAHE (1546-1601) 


ASTRONOMY 


TycHo BRAHE was the eldest son of a Swedish nobleman, 
and was born on the family estate (Knudstrup) near the 
town of Helsingborg, which stands on the narrow strait 
between Sweden and Denmark. Twenty-three years previ- 
ously the former had become independent of Danish sov- 
reignty, and under the wise and capable reign of Gustavus 
Vasa, Tycho passed his youthful years. When the boy had 
reached the age of ten his father died, and he passed under 
the care of his uncle, Otto Brahe. By that time he had not 
only learned to read and write his native language well, 
but had begun the study of Latin, and by the age of thir- 
teen was so well grounded in that language and the funda- 
mentals of mathematics, that it was considered time to send 
him to the University of Copenhagen, to specialize in those 
studies which led up to the profession of the law, for which 
his uncle destined him. In the following year (1560), an 
eclipse of the sun had been predicted for August 21st, and 
the educated world of the day was naturally excited over 
the coming event. When it began precisely at the time set, 
Tycho was so moved, that he resolved to make himself the 
master of a science that could foretell accurately an event 
so marvelous. | 

In 1562 he was transferred to the University of Leipsic 
to finish in law. But he exhibited no inclination for the 
profession, and when his uncle died in 1565, leaving him, 


The Sixteenth Century 77 


at the age of 19, in possession of a handsome income, he 
took his future into his own hands, and devoted his ener- 
gies to astronomy, much to the disgust of all his relatives 
except a maternal uncle, Steno Bille, who unhesitatingly 
encouraged him to follow his natural bent. Leaving his 
native land he went to Wittemberg in Saxony, early in 
the spring of 1566, but moved to Rostock in Mecklenburg 
the following year. Here he became involved in a quarrel 
with a Swedish nobleman, with whom he fought a duel with 
swords in total darkness, with the result that his opponent 
sliced off the entire front of his nose, which naturally ended 
the contest. The damage was repaired by cementing on 
his face an artificial nose, constructed mainly of gold and 
silver which, for the balance of his life, was worn without 
serious discomfort or disfigurement. 

Late in 1568 he journeyed to Augsburg in Bavaria, and 
there made the acquaintance of the brothers, John and Paul 
Hainzel, both astronomical enthusiasts, and also men of 
some means. To them he explained his desire to set up a 
quadrant of some twenty feet radius for observational pur- 
poses, the drawing for which so impressed them that they 
not only offered to bear the expense of constructing it, but 
to provide a suitable site for its installation in one of the 
suburbs of the city where Paul had a country home. To 
this was later added a sextant of 5-foot radius, and with 
these two primitive instruments many successful observa- 
tions were made. Towards the end of 1571, by which time 
his fame had spread throughout Europe, he made a visit 
to his home town, and met with a warm reception from 
both friends and relatives, and particularly from his 
Unele Steno, whose encouragement for his early ambitions 
was now fully justified. This relative now offered him 
quarters on his own extensive estates for an observatory, 
and when he learned that his gifted nephew was also inter- 
ested in alchemy—which, at the time, was considered quite 
as reputable a field of inquiry as astronomy—agreed to 
provide him also with a fully equipped laboratory. This 
munificent offer was eagerly accepted by the young man, 
who was then in his 25th year, but was not immediately 


78 Beacon Lnghts of Science 


acted on. At the time Tycho was, of course, aware of the 
theories of the Universe that had been propounded by 
Copernicus a quarter of a century previously, but there are 
reasons for believing that he had never read the ‘‘Trea- 
tise’’ that set them forth, and it is certain that he rejected 
the general conclusions of the work, on the ground that 
they were contrary to the teachings of the Scriptures, and 
of the Church, of which he claimed to be a devout member. 

In the fall of the year (1572) a ‘‘nova’’ suddenly ap- 
peared in the constellation of Cassiopeia. It was first seen 
by Brahe on November 11th, but had been detected by 
others as early asin August. It was an unusually brilliant 
one, remaining visible for over a year, and disappearing 
only in March, 1574. At its maximum it was the equal of 
Sirius in brightness. Tycho was wonderfully impressed 
with the phenomenon, and made observations every clear 
night during its continuance, which later were published. 
These added so greatly to his reputation that the King, 
becoming interested, asked him to deliver a course of lec- 
tures on the subject. Here it should be mentioned that 
about a year previously Tycho had married a girl of the 
peasant class, to the deep offense of his relatives. But the 
success of his lectures, and the favor with which they were 
received at Court, much more than overbalanced the dis- 
pleasure of his relatives in the public mind. Tycho, how- 
ever, was so angered at the slights his wife had received 
at their hands that he determined to abandon Sweden as 
a residence, and early in 1575 left for Germany to find 
a more congenial environment. Going first to Hesse Cassel 
he spent a week or more in delightful association with the 
Landgrave of that principality, who was one of the noted 
astronomical enthusiasts of the day. From there he tray- 
eled into Switzerland, and after deciding upon Basle as 
a desirable location, and making a short visit to Venice, 
he began his return journey to Sweden to fetch his family 
to the new home. While preparing for the move he re- 
ceived an offer from the King of Denmark and Norway of 
a grant for life of the island of Huen, situated in the 
narrow strait ketween Denmark and Sweden, on which 


The Sixteenth Century 79 


would be erected at royal expense all the buildings for such 
an observatory and laboratory as Brahe might plan, and 
equipped with all the instruments and appliances neces- 
sary for his work. The offer also included a liberal sub- 
vention to cover operating and maintenance costs, a house 
for his family and a salary for his support. Naturally, 
such a flattering proposal was at once accepted, and before 
the end of the year construction upon a most elaborate scale 
began. The ultimate total cost of the establishment was 
close to one million dollars, of which Brahe contributed 
nearly one half, almost impoverishing himself in the oper- 
ation. He gave it the name of Uranienborg. 

Here Tycho passed the next twenty years of his life, dur- 
ing which he not only made a large number of valuable 
and important stellar and planetary observations that 
added greatly to the current stock of astronomical know!- 
edge, but also spent much time in the laboratory in re- 
sultless experiments in alchemy. It was in fact his devo- 
tion to the latter that finally encompassed his downfall. 
In 1588 the King died, after a notable reign of 29 years. 
His son, Christian IV, who succeeded, was but 11 years 
old at the time, and naturally was easily influenced and 
controlled by those around him. In 1591 this boy sove- 
reign made his first visit to Uranienborg, accompanied by 
a large party of courtiers, some of whom disapproved 
strongly of the favors that had been bestowed on Brahe, and 
most of whom were more interested in pushing their own 
fortunes than in advancing the cause of science. Further- 
more, an opinion prevailed that no discoveries of any im- 
portance or value to the State had resulted so far from the 
extensive and costly laboratory experiments that Tycho had 
been conducting. It was not long before these unfriendly 
individuals began to make trouble for him, and in 1597 his 
situation became so unpleasant that he moved his family 
from the island to Copenhagen, taking with him his smaller 
instruments, and all his books and notes. A little later 
he appears to have chartered a vessel, loaded into it as 
much of his larger instruments and chemical apparatus as 
could be easily moved, and with his family sailed for 


80 Beacon Lights of Science 


Rostock on the Mecklenburg coast. From there, having 
been cordially invited, he took his wife and children to the 
estate of his old friend Count Henry Rantzau, at the castle 
of Wandesburg, near the city of Hamburg, where he was 
made very welcome and urged to remain as long as he 
might desire. Rantzau suggested an appeal to Emperor 
Rudolph of Bohemia, who was a notable patron of the 
mystical arts, and to make this as strong as possible Tycho 
went to work at once to compile a memoir of the results 
ot his life’s labors to date. With that in manuscript he 
started for Prague, and received a most royal welcome from 
the sovereign. Rudolph at once gave him a pension, a 
country estate, and finally offered the castle of Benach, 
in the suburbs of the city, as a site for his instruments and 
apparatus. In August, 1599, he took possession, dispatched 
an assistant to bring his large instruments from the island 
of Huen, and his family from Wandesburg. Later, finding 
that the surroundings of Benach were not as suitable for 
his work as he at first thought, he begged the Emperor to 
allow him residence in Prague. He was at once permitted 
to establish himself temporarily in the royal edifice, and to 
set up his instruments in its gardens or park, and in the 
buildings surrounding it. The Emperor then crowned his 
benificenees by purchasing a house for him in Prague, and 
into this Tycho moved with his family in February, 1601. 

But before the year had come to an end, and just as he 
was beginning to enjoy the comforts and honors of his new 
home, he fell ill, and in less than two weeks passed away 
at the early age of less than fifty-five years. 

Brahe was of medium height, with reddish-yellow hair, 
a ruddy complexion, and, if the portraits preserved of him 
are correct in detail, a dome-shaped head, a prognathous 
profile, with full lips (the upper unusually short) and the 
eyes deep set. These cranial characteristics indicate large 
observational capacity, combined with a vigorous physique, 
a sanguine and rather irritable temperament, and a love 
of the marvelous. In conversation he was brilliant rather 
than impressive or logical, somewhat impatient at opposi- 


, 


The Sixteenth Ceutury 81 


tion, yet generally kindly and generous to those around 
him. : 
In estimating his position as a scientific man it is neces- 
sary to remember that in his day the study of the heavens 
was carried on mainly in the hope of enabling the student 
to cast correct horoscopes, and that those who interested 
themselves in such work were really astrologers, and in 
no sense astronomers, as the word is used today. Further- 
more, practically all the patrons of the art, the rulers and 
men of wealth who encouraged and supported celestial ob- 
servation and study, did so mainly in the hope that dis- 
coveries might ensue that would redound to their material 
benefit, or enable them to avoid threatened danger or pro- 
long life. The same was true of the alchemistic art, which 
had for its object the discovery of ways to transmute the 
base into the precious metals, and to produce elixirs or 
drugs that would prolong life or cure its ills. Neither 
astronomy nor chemistry as sciences had yet been born. 
Brahe was really an astrologer and alchemist, and no 
more. He held to the Ptolemaic cosmology, and rejected 
that of Copernicus, not because the former appealed to his 
reason and the latter did not, but because the authorities 
of the Church of the day supported the one, and condemned 
the other. Into the matter of the reasonableness of this 
position he had no inclination to inquire. Hence, though 
he was a brilliant and ingenious inventor of appliances for 
observational use, and with their aid made a very large 
number of observations of note, they led to nothing in the 
way of a better understanding of the cosmos. The same 
may be said of his laboratory work, all records of which 
have disappeared, if notes were ever made. From this 
estimate of his character it is not to be concluded that he 
was a conscious pretender or charlatan. He deceived no 
one more than he deceived himself. He was the uncon- 
scious egoist of his day, yet one whose family life was 
elean and commendable, who attracted many sincere ad- 
mirers, and who retained through life a few devoted 


friends. 


82 Beacon Laghts of Scvence 


STEVIN (1548-1620) 


MATHEMATICS 


Stmon SteEvin, better known among his contemporaries 
as Stevinus, was a native of Bruges in Belgium. Of his 
early life little is known, but that he was a man of good 
education and fine powers is proven by the fact that he 
held important positions under Prince Maurice of Orange 
in the capacity of civil and military engineer, where his 
scientific qualifications were exercised to the great advan- 
tage of his patron. He is best known as the introducer of 
the decimal system of notation now universally in use, and 
which he ventured to predict would ultimately result in 
the evolution of a decimal system of coinage, weights and 
measures, aS has since been realized in the metric system. 
In addition to this very important forward step, he made 
a number of valuable contributions to the advance of 
knowledge in the domain of mechanics and physies, the 
most notable of which were those of the resolution of forces, 
the equilibrium of forces on the inclined plane, and the 
demonstration that the pressure of a liquid is independent 
of the shape of the containing vessel, and is determined 
only by the area of its base and the depth of the contained 
liquid. His writings were published in Holland in 1568, 
and in 1634 were translated into French and published in 
Paris. 

The invention of numbers and of numerical systems is 
one of the earliest achievements of civilization. We owe to 
the Arabs our present list of nine digits and the cipher, but 
it is thought that they, in turn, derived them from India. 
Who first conceived the idea of representing these units by 
signs, instead of by the written word of their name, is un- 
known. Originally each probably consisted either of a rude 
pictograph of one or more of the fingers of the hand, or of 
the first letter of the written word. These everywhere be- 
came conventionalized sooner or later, until all semblance 
to origin disappeared. The cipher is supposed by some to 
represent the two hands closed and pressed together, with 


The Sixteenth Century 83 


the fingers and thumbs interlocked. From the western 
Arabs our figures came to Europe via Spain and the Moors, 
under the name of the Gubar numerals, through the efforts 
at first of Pope Sylvester II (935-1003), who was a noted 
mathematician of his day, aided later by the labors of 
Leonardo of Pisa—better known as Fibonacci—about the 
year 1200, and in the following form: 


124264586620 


When it occurred to Stevinus to place the decimal point 
on the right-hand side of one or more digits, and to estab- 
lish the figures following it as representative respectively 
of tenths, hundredths, thousandths, ete., a wonderful step 
in advance was taken. The new notation met with imme- 
diate approval and adoption among the educated, while 
the old one of fractions (1%, 14, 1%, ete.) was abandoned to 
the uneducated, and thus acquired their present name of 
common or vulgar fractions. 

Among the ancient Egyptians and Babylonians the scales 
of 12 and of 60—and their multiples—were employed, and, 
to a much more limited extent, scales of two (binary) and 
three (ternary). It is interesting to note that the first 
has survived until today in the English system of money, 
and in the English and American systems of weights and 
measures; while the second remains with us in the divisions 
of the circle into degrees, minutes and seconds; and both 
combined, on the faces of the clocks and watches of the 
civilized world. 


NAPIER (1550-1617) 


MATHEMATICS 


JoHN Napier came of well-to-do parents, living in 
Murchison, a small town near Edinburgh, Scotland; and 


84 Beacon Lights of Scrence 


was educated at St. Andrew’s University near Dundee, 
finishing off at the University of Paris. He was naturally 
endowed with fine mathematical faculties, and also with a 
disputatious and obstinate temperament, which inclined 
him to extreme views in religious and other matters. These 
characteristics involved him during the earlier parts of 
his life, at times, in awkward and regrettable situations, 
one instance of which was the publication in 1594 of a 
pamphlet entitled ‘‘The Plaine Discovery of the Whole 
Revelation of St. John.’’ This, like Sir Isaac Newton’s 
disquisition about a century later on the Bible books of 
Daniel and Revelations, was an example of the unfortunate 
trend of the day among men of speculative minds and 
deeply religious temperament, to attempt the explanation 
of assumed mysteries, by means of the few scientific prin- 
ciples by then available. 

This phase of Napier’s character lost its intensity as he 
neared middle age, by which time the idea of Logarithms 
had come to him, and engaged his attention so thoroughly 
that practically the balance of his life was devoted to the 
computation of logarithmic tables. His discovery of the 
system has justly earned for him an enduring fame. 

The theory of Logarithms is one not easy of comprehen- 
sion by the lay mind. Moreover, since its development by 
Napier, it has been further developed by later mathema- 
ticians, though the principle at its foundations remains sub- 
stantially the same, as also the results sought. These, in 
effect, are the substitution in most cases of the easy proc- 
esses of addition and subtraction, for the more difficult ones 
of multiplication and division, and the shortening of those 
of multiplication and division when they cannot be avoided. 

Logarithmic tables give, for each rational number-—— 
whether an integer like 45 or 247832, or a fraction like 2.7 
or 1846.432911—a logarithmic number, which is used in 
its place, as illustrated in the following example. 

Let it be required to ascertain the circumference of the 
moon at the equator in inches, calling its radius 1061 miles. 
To determine the amount it will be necessary to multiply 
together the following natural numbers: 


The Sixteenth Century 85 


Bartling. of. the moon: Imi milesy wii ok csves 1061 
PEGLIO! UP LemeLer / CO STROVE. oye a sie ds vine oe 2 
Ratio of circumference to diameter......... 3.1415927 
OASIS leet i Fos tia en ek sd oe sie lo es 5280 
COT OGL IN, TBODCS «7s mealies oe bese e's. mcaiehe 12 


If now, instead of performing those multiplications, we 
find, in a table of logarithms, the logs of these natural 
numbers, the problem becomes one of simple addition as 
follows: 


DAMPERS MU DS His) oir tT eae Be og chs wt bsp oie dial 3.0257154 
Log of PEO oh ata MAEM ieee tee a, Awl ARS gUG00 ora! Ska, 0.3010300 
Log of DRAM oe ener ets wiste aN ales aisle 04 0.4971499 
Pee OOO i) LT (Bons ha telstra OA dioke CUO ee 3.7226339 
AON MN 15 BW tt oa Si ans er aaa atid ells "eh mle’ fips od bok 1.0791812 
PERG MUNN OL WHICH AG con fs ak le sates e wield Os ods bs 8.6257 104 


Finally, looking again in the table for the natural num- 
ber corresponding to this last logarithmic number, it is 
found to be between the numbers 422,387,444 and 422,- 
388,330, the mean of which would be 422,387,887, which 
is the answer. 

The system is of extended use and advantage among 
astronomers, engineers, and others who have long and la- 
borious computations to make, and also for the purpose of 
proving the accuracy of calculations made in the ordinary 
way. 


GALILEO (1564-1642) 


ASTRONOMY 


ONE of the most illustrious of Italian scientists, Galileo 
lived in Pisa, and was the eldest of a family of six children. 
His parents belonged to the nobility, but their means were 
extremely limited. The boy, however, received a good edu- 
cation in the fundamentals, and at the age of 17 entered 
the University of Pisa with the intention of making the 
medical art his vocation. He had previously exhibited 
considerable ability in musie and drawing. These predilec- 
tions, added to a naturally inquiring mind, led him to the 


86 Beacon Lights of Science 


field of the higher mathematics, and to such instruction in 
physics as could be obtained at the time. In the latter he 
exhibited so much capacity and ingenuity as to attract the 
attention of Ferdinand de Medici, the reigning Duke of 
Tuscany, who secured him the post of lecturer (or tutor) 
in mathematics. By this time all thoughts of a medical 
career had been abandoned by both his father and himself, 
and all his youthful enthusiasm was applied to a critical 
examination of the philosophical systems—mainly Aristot- 
lean—being taught at the time. These did not suit him, 
and with the ardor and indiscretion of youth he condemned 
them so openly and so vigorously, as to draw the return 
fire and ill will of all conservatives within sound of his 
voice. One of his major victories over the mechanical ideas 
of the day was his demonstration from the summit of the 
famous leaning tower of Pisa of the true law of falling 
bodies. By the Aristotlean doctrine, of two bodies of un- 
equal weight, but otherwise similarly conditioned, the 
heavier would reach the earth the sooner. And though 
Galileo repeatedly demonstrated the inaccuracy of the 
theory, the enmity aroused against him was so great that 
when the chair of mathematics at the University of Padua 
was offered to him in 1592, he deemed it advisable to accept 
and move there, and take with him his mother and sisters, 
the care of whom had devolved upon him by the death of 
his father the year before. There, though his salary was 
but 180 florins (about $375), and he was compelled to 
undertake outside tutorial work, he found time to pursue 
his investigations into the laws of physics and mechanics, 
to perfect several inventions, and to complete a number of 
manuscripts of a controversial nature, nearly all of which 
were devoted to criticism of the current philosophies of 
the times. It was during this period that he became a con- 
vert to the Copernican theory of the Cosmos, nevertheless, 
for some time thereafter he continued to teach the Pto- 
lemaic theory in his classes, excusing himself in a letter to 
Kepler written in the year 1597, by stating that he had not 
yet dared to publish his refutation of it. But he hoped to 
be soon firmly enough established to do so. 


The Sixteenth Century 87 


By this time Galileo had acquired so much celebrity as a 
polished and interesting lecturer that many members of 
the nobility attended his classes. This added so greatly to 
the reputation of the university that in 1598, when his con- 
tract was renewed for a second period of six years, his 
salary was doubled; and when that term came to an end 
in 1604, it was again increased to 520 florins, placing him, 
at the age of 40, in most comfortable financial condition. 
Possessed of a pleasing personality, and gifted oratorically, 
his lectures drew so well that no auditorium in Padua was 
large enough to hold those who wished to attend, and it 
was often necessary to adjourn to open-air meetings. 

It was towards the latter part of the third term of his 
professorship, that the most interesting event in his career 
at Padua occurred. Throughout all he had retained the 
confidence and admiration of his former patron, the Grand 
Duke of Tuscany, who died in 1609. He was succeeded by 
his son, Cosmo, who, in his youth, had been a favorite pupil 
of Galileo. Cosmo, desiring greatly to have his former 
preceptor return to Pisa, made him a most flattering offer 
to that end. While the details of it were under considera- 
tion, Galileo paid a visit to a friend in Venice, and at his 
house heard of a curious instrument said to have been in- 
vented by a Hollander a year previously, which possessed 
the strange power of making things at a distance appear 
as if near by; and a few days afterwards he received a 
letter from a friend in Paris, giving a rough description 
of it, to the effect that it was a tube carrying a glass lens 
at both ends. Galileo, greatly excited, returned at once to 
Padua, and looking over the notes of his studies on the 
refraction of light, procured a couple of lenses from a 
spectacle maker (one of which was plano-convex and the 
other plano-concave), and set them in the opposite ends 
of a lead pipe. Then, applying his eye to that end which 
earried the latter, he found himself in possession of an 
instrument which produced the effect sought, though it 
magnified only to the extent of three diameters, as we 
would now say. Wonderfully excited he returned at once 
to Venice, and exhibited the instrument to his friends 


88 Beacon Lights of Scvence 


there. Among them it aroused intense interest, and when 
the news spread, hundreds of the upper class people of the 
city flocked to the house where he was lodged to see the 
device. 

Galileo remained in Venice several weeks, exhibiting his 
invention. So greatly did it enhance his reputation that 
the Doge invited him to present it to the State, intimating 
at the same time that he would not regret the gift. Nat- 
urally, he compled at once, and in response he was ap- 
pointed for life by the Senate to the professorship at the 
university, and his salary increased to 1000 florins. Of 
course, the instrument was a mere toy. But Galileo, who 
perhaps was the only man then living with some technical 
understanding of the optical principles involved in its con- 
struction, went to work at once to make another of greater 
power. The lenses that were sold in the spectacles of the 
day were very poor affairs. The glass of which they were 
made was good enough, but the art of grinding and polish- 
ing curved surfaces had been but slightly developed. How- 
ever, in due time he had finished an instrument which, ac- 
ecrding to his calculations, should magnify to the extent of 
thirty diameters, and on the first clear night following he 
turned it on the full moon. His wonder and delight at 
what was then for the first time revealed to the eye of man, 
ean better be imagined than described, for now the unde- 
fined markings that had baffled observers since the dawn of 
human time, were resolved into a multitude of gigantic 
mountain ranges, surrounding vast and deep crater-like 
valleys, across which the shadows of the craggy summits 
drifted as the satellite turned through space under the 
glare of the sunlight. Today the face of the moon is 
mapped almost as accurately as that of Africa. To Galileo 
it must have been, even under his crude telescope, like an 
apparition of a new world, of which he was the first dis- 
eoverer. 

But a still greater surprise was in store for him when 
he directed his instrument first, to such of the planets as 
were sufficiently above the horizon to be examined with 
advantage, and later to the fixed stars. For while the 


The Sixteenth Century 89 


latter still remained simply minute and twinkling points 
of light, just as they appeared to the naked eye, the former 
were now revealed as well-defined disks, or parts of disks in 
the case of Venus and Mercury, whose phases were as 
clearly revealed as those of the moon. 

Galileo, now thoroughly aroused, set to work upon the 
construction of a still more powerful telescope, and when 
it was completed he trained it on the night of January 7th, 
1610, on the planet Jupiter, which was then in excellent 
position for examination. At once he detected three new 
stars close to it, and nearly on a line, two being east and 
the other west of it. Believing them to be simply hitherto 
undiscovered ones, he paid no particular attention to them. 
But on the following night, when he again examined the 
giant planet, he was surprised to see the stars differently 
arranged. All three were now on the west side, and were 
much nearer to each other. This astonished him greatly, 
and we can imagine his disappointment when the night of 
the 9th proved too cloudy for observation. But that of the 
10th was all that could be desired, and when his instrument 
was placed, one of the supposed stars had totally disap- 
peared, while the other two were on the east side of Jupiter. 
Galileo now began to fear that his telescope was in some 
way at fault, and was greatly disturbed. When he gazed 
through it again on the next night he still could find only 
two of these strange stars, and both to the east as before, 
yet one of them now seemed to be twice as large as the 
other, though heretofore all had appeared to be about the 
same size. On the night of the 12th he again found them 
in altered positions, and of changed magnitudes, and on 
the 13th he detected a fourth star in the same line as the 
other three. 

At last the meaning of the phenomenon dawned on the 
mind of the delighted astronomer; but he continued his 
observations nightly until the 22nd, when, feeling certain 
of his facts, he gave publicity to them on the 24th, in a 
pamphlet under the title of Nuncius Siderius, dedicating 
it to his patron Cosmo. In effect the document stated that 
the planet had four satellites, which revolved around it as 


90 Beacon Laghts of Science 


does the moon around the earth, and the planets around 
the sun. 

This remarkable disclosure established forever the fame 
of Galileo, dealt a crushing blow to the Ptolemaic theory 
of the universe, and established that of Copernicus beyond 
any question, though the supporters of the former fought 
the change bitterly for some years, as he was to learn to 
his sorrow. : 

Being strongly urged to return to Pisa by his patron 
Cosmo, and also as sincerely invited to remain at Padua, 
and become an honored citizen of the Venetian republic, he 
found the choice a difficult one, which caused much disap- 
pointment in the latter when he decided in favor of Pisa. 
This passed away, however, with all except the unworthy, 
for it was recognized that upon equal terms, or even some- 
what unequal, one would naturally prefer his native land 
to foreign residence. But the brillianey of his discoveries 
now began to bring him enemies as well as friends, for 
Galileo was of a temperament that delighted in controversy, 
and an adept in the art. Having produced uncontrovert- 
ible proofs that the orthodox conception of the Universe 
could no longer stand, his strongest foes arose from the 
ranks of the Church; but so astonishing were the effects his 
discoveries had produced among intelligent laymen, that 
his opponents for some time made little progress. In fact, 
his reputation continued to grow, in consequence of his 
further discoveries. He was the first to detect the rings of 
Saturn, but having made his observations at a time when 
their plane was approaching parallelism to the line of 
sight, he misunderstood the phenomenon, and announced 
that Saturn had two moons, which chased each other at 
equal distances from it. Somewhat later, when the disk 
became simply a line, and then totally disappeared, he 
was nonplussed, and is said to have exclaimed: ‘‘Has 
Saturn indeed devoured his children?’’ He did not live 
to solve the mystery. Somewhat later he observed and 
studied in detail the phases of Venus, which exactly dupli- 
cate those of the moon as viewed from the earth. 

In 1611 Galileo made a visit to Rome, taking with him 


The Sixteenth Ceutury 91 


one of his most powerful telescopes, and was accorded a 
most hearty welcome even from the dignitaries of the 
Church, who, though they feared the effects of his discov- 
eries, could not deny his genius, nor the celestial phenomena 
which he made visible to them through his telescope. But 
in certain highly orthodox circles he was regarded as a 
dangerous enemy of revealed religion, and was closely 
watched in the expectation that sooner or later some speech 
or act would make him vulnerable. It was from these that 
danger was to be expected, and in due time it came. 

At this stage of his career Galileo was approaching mid- 
dle life, and had contracted a chronic ailment that was be- 
ginning to affect his temperament and judgment. Natur- 
ally impatient at opposition, as is often the case with men 
of high intelligence; confident of his own powers, proud 
of the discoveries he had made, and trusting too much to 
the towering position he had attained among thoughtful 
people everywhere, he displayed at times a recklessness in 
speech and action that caused distress to his best friends. 

His troubles began when an open attack was made on 
him from the pulpit by a Dominican friar named Caccini. 
To this Galileo made a logical but rather intemperate and 
sarcastic reply, and the result was an appeal to the Inqui- 
sition. This body met in Rome in 1615, and after consid- 
ering the evidence offered, passed judgment to the effect 
that Galileo must either renounce the Copernican theory 
and cease to teach it, or be imprisoned. Making mental 
reservations, the astronomer complied with the orders of 
the court, and was at once set free. But he did not keep 
his promise. In fact, he violated the spirit of it outrage- 
ously, as well as the letter, and this cost him the friendship 
of many churchmen who admired his genius, and who 
wished him well—among them the Pope himself. During 
the succeeding years, whenever the condition of his health 
permitted him to teach or write or engage in controversy, 
he did not hesitate to maintain his views of the nature of 
the Universe, and being by now a confirmed invalid, and 
regarded by many as mentally unbalanced, he was allowed 
much latitude of expression, on the theory that he could 


92 Beacon Lights of Science 


not live much longer anyway, and that if given enough 
rope he would hang himself. Galileo mistook this leniency 
for fear of his ability and standing with the intelligentsia, 
and went from one imprudence to another, without regard 
at times for even the ordinary courtesies, until it be- 
came impossible for the Church to ignore him any longer. 
And though the newly elected Pope (Urban VIII) was a 
strong friend and ardent admirer, Galileo did not hesitate 
to alienate even him by the publication in 1632 of a con- 
troversial pamphlet in which this valuable friend—under 
a fictitious name was held up to ridicule. This production, 
which was entitled ‘‘The System of the World, by Galileo 
Galalei,’’ was presented in the form of a dialogue between 
three individuals, named respectively Salviate, Sagredo and 
Simplicio. The first represented himself, the second a 
friend of ability and wit who asks questions, suggests 
doubts, ete., while the third was the ardent but poorly 
equipped churchman who, adhering strictly to the out- 
grown theories of Aristotle, Ptolemy and the Fathers, gets 
the worst of it in all encounters and is mercilessly lam- 
pooned. The work was really a brilliant one, displaying 
Galileo’s logical talents at their best, but also revealing, in 
its satire and contempt, the depth to which by that time 
his moral nature had sunk. It was impossible for the 
Church to ignore it without confession of total defeat, for 
the enemies of the astronomer did not hesitate to assure 
the Pope that the author of the pamphlet had purposely 
intended the character of Simplicio to be a representation 
of himself. In the spring of 1633, in response to the sum- 
mons of the Holy Office, Galileo, then in his 69th year, pre- 
sented himself for trial. His physical condition was de- 
plorable, yet so strong was his self-esteem, and so aston- 
ishing his blindness to the position in which his folly had 
placed him, that he could not grasp the necessity on the 
part of his opponents to silence him forever at any cost. 
As the trial proceeded it slowly dawned on him that it was 
not a matter of argument as to the truth or falsity of the 
Copernican System, and his advocacy of it, but simply 
whether he or his accusers possessed the most power. And 


The Sixteenth Century 93 


though his friends—of whom many in high places still re- 
mained faithful—made every possible effort to save him, 
they found against them a power which, at the time, when 
fairly aroused, was irresistible. 

During his trial, Galileo was treated with extraordinary 
outward courtesy and consideration by his judges. Yet 
not for a moment was the issue in doubt, so far as they 
were concerned. No line of defense that he put forward 
could overcome the fact that he had broken the promises 
made at his first trial, and on the 22nd of June his sentence 
was pronounced. Galileo was both physically and mentally 
unable to resist. On his knees before the officials of the 
Inquisition, in the most solemn and impressive of surround- 
ings, and with his hands upon the Bible, he vowed never 
again to teach the doctrine of the earth’s motion and the 
sun’s stability. After which he was committed to the 
prison of the Inquisition. From there, at the end of only 
a few days of confinement, he was allowed to go to the 
palace of the Tuscan ambassador at Rome, and later to 
the home of Archbishop Picolommini at Sienna. Here he 
was a welcomed guest for nearly six months, at the end of 
which time he was permitted to retire to his home near 
Florence. There, in strict retirement and seclusion from 
the world and all but the most intimate of his friends, he 
passed the remainder of his days. His death occurred in 
January, 1642, at the age of 78, nine years after the pass- 
ing of the sentence which terminated his active career. 
Towards the end of it both his sight and hearing failed. 

In person Galileo was of middle height and sturdy build, 
with a fair complexion, and hair of slightly reddish tinge. 
His features were strong, rather thin, finely cut, the lips 
were full, the nose broad at the nostrils, the ears rather 
prominent, and the eyebrows somewhat upturned out- 
wardly. His temperament was a combination of the san- 
guine and choleric, which often led him into positions that 
would have been avoided by the exercise of a little tact. 
His intellectual equipment was of the highest order, but 
there was a deficiency of moral courage, and a disinclina- 
tion to be bound by even such lax moral conventions as 


94 Beacon Lights of Science 


were current in his time. The ailment from which he suf- 
fered during the last third of his life, was one which it is 
now known clouds the moral nature as much as, if not 
more than, it impairs the physical, and to this must chari- 
tably be ascribed his failure to observe the promises made 
at his first trial, and his abject surrender at the second. 
His published letters to the Abbé Castellini and the Grand 
Duchess of Tuseany (1613), which brought about his first 
indictment, were placed in 1616 on the Index Expurgator- 
ius, at the same time as the ‘‘Treatise’’ of Copernicus (pub- 
lished in 1543), and Kepler’s ‘‘ Epitome of the Copernican 
Theory,’’ which appeared in 1614. 


KEPLER (1571-1630) 


ASTRONOMY 


JOHN KEPLER, the son of upper class Protestant parents, 
was born in the city of Weil, in the duchy of Wiirtemberg, 
Germany. He was a premature child, and with difficulty 
survived his infancy. At the age of five his parents, being 
compelled to go the Netherlands, left him with his grand- 
father at Limberg. There he began to attend school at 
the age of six years. But in 1579 it became necessary for 
him to join his parents, and for a time aid them with his 
services. However, in 1586, they were able to place him 
in school again at the monastery at Maulbroom, which held 
the rank of a preparatory institution for the University of 
Tiibingen. There he took his degree of Bachelor in 1588 
and of Master in 1591, in both cases with eredit. 

His natural inclination during these student years was 
towards philosophy, but he was well advanced in the higher 
mathematics by the time he left, and had become an ardent 
advocate of the Copernican system of the Cosmos. In 1594, 
he was offered and accepted the professorship of astronomy 
at Gratz, in Styria; and though he frankly considered him- 
self unfit for the position, he took it because of the salary 
it carried. But he worked and studied hard, and soon 
found his powers and interest growing. At this period of 


The Sixteenth Century 95 


his life he devoted much thought to a fruitless effort to 
arrange the orbits of the five planets then known besides 
the Earth in some kind of a mathematical sequence or 
order, on the basis, first of the relations which plane figures 
—triangles, squares and polygons—hear to the circle, and 
then on the relations between solids—tetrahedra, cubes 
and polyhedra—and the sphere; and in 1596 published a 
pamphlet on the subject which, though it brought him a 
considerable notoriety among the undiscriminating public, 
had no real value. 

In 1597 he married, and shortly thereafter, on account of 
religious quarrels between the Catholics and Protestants 
of Gratz, he, being an avowed Lutheran, thought it best 
to retire with his wife into Hungary. He was recalled in 
1599, but finding conditions at Gratz still unsatisfactory, 
he decided to make a visit to Tycho Brahe, who was then 
living at Prague, under the patronage of Rudolph of Bo- 
hemia, and arrived there early in the year 1600. Here he 
passed two very disturbing years, at times on the most 
friendly terms with Tycho, and at others in violent enmity. 
The elder, recognizing the ability of the younger man, de- 
sired to help him, but feared his too speculative tendencies ; 
while the younger, misinterpreting the motives of Tycho, 
became at times suspicious of his good faith. These differ- 
ences, however, were finally composed with credit to both 
parties. In 1601 he became Tycho’s official assistant, and 
on the death of the latter in the same year he was advanced 
into his position by the Emperor at a handsome salary, 
which, however, was always in arrears. Kepler now settled 
down to congenial work, and soon acquired an enviable 
standing, largely because of the valuable pamphlets and 
books he was able to publish, on the foundation of the 
enormous amount of observational data which had passed 
into his hands at the death of Tycho. 

In 1604 the world was startled by the sudden appearance 
of a new star in the constellation of the Serpent, which 
rivaled in brilliancy that of 1572, but lasted only a few 
months. Kepler published an account of it, but the docu- 
ment was not a creditable one, because in it he indulged 


96 Beacon Laghts of Scvence 


in many foolish and wholly unscientific speculations and 
predictions, which naturally were never realized. About 
this time, to relieve himself from pressing financial obliga- 
tions, he undertook to cast horoscopes, which even at this 
stage of his development he certainly knew were entirely 
futile. But the age was one in which astrology still flour- 
ished, and credulity was rampant even among the educated 
classes. He simply took advantage of these circumstances, 
and of his reputation, to increase his income, while at the 
same time continuing his scientific studies. In 1606 he 
published a work of value on the refraction of light, and 
in 1609 his really great work appeared under the title of 
‘‘The New Astronomy.’’ For the data upon which his 
notable conclusions were drawn he was indebted to the 
observations made by Brahe and their extraordinary aceu- 
racy, considering the instruments employed in making 
them. Kepler, however, deserves the eredit of having de- 
duced from them at least two of the three laws which are 
known by his name. These are: 

1. That all the planets travel around the sun in ellipti- 
eal orbits (instead of in circles as Copernicus taught), with 
the sun at one of the foci. 

2. That the radius vector joining each planet with the 
sun, traverses equal areas of the plane of the orbit, in equal 
periods of time. 

3. That the square of the time of revolution of each 
planet around the sun, is proportional to the cube of its 
mean distance from that luminary. 

The last was not given to the world until 1619. 

In 1611 he added still further to his well-earned fame 
by publishing a work of high merit on the laws of vision, 
and the construction of the astronomical telescope, consist- 
ing of two convex lenses, instead of the plano-convex and 
plano-coneave ones of the first Galilean instrument. 

Kepler was now at the summit of his career, but con- 
tinually harassed by financial difficulties, due to the failure 
of his patron to pay him his full salary. The Emperor, 
in his turn, was experiencing equal trouble in collecting his 
revenues, owing to the continual internal and external dis- 


The Sixteenth Century 97 


turbanees of the times. Kepler’s domestic affairs were also 
in a pitiable state, through privations and illnesses, which 
culminated in the death of his favorite son from smallpox, 
and of his wife from one of the infectious fevers so preva- 
lent in central Europe at the time. In his struggles against 
these misfortunes he endeavored to secure a professorship 
at Lenz, in Austria, but Rudolph was unwilling to have 
him leave Prague. In 1612 this enlightened ruler died, and 
was succeeded by his brother Matthias, who allowed Kepler 
to assume the position at Lenz temporarily, while still re- 
taining his post as Imperial Mathematician in Bohemia. 

At Lenz he remarried, and among other literary activities 
of a more dignified and worthy nature, he published an 
almanac, which he himself held in contempt, calling it, in 
a letter to a friend, ‘‘a vile, prophesying thing, which is 
scarcely more respectable than begging,’’ but which, on 
account of his reputation, met with a lively reception 
among the masses, and so assisted him financially to a con- 
siderable extent. In 1617 he was invited to the chair of 
mathematics at the University of Bologna, but appreciating 
the persecution he would inevitably encounter in such a 
stronghold of Catholicism as Italy, he wisely declined the 
flattering offer. Even at Lenz he was harassed to some 
extent by bigots, nor was he much better off financially 
than at Prague, for his salary was always in arrears. 

In 1619 Matthias died, and was succeeded by Ferdinand 
III, who continued Kepler as Imperial Mathematician, 
promised to try to pay up his arrears of salary, and to 
find money to publish the Rudolphine Tables, the comple- 
tion of which had passed into his hands at the death of 
Brahe. Before returning to Prague, however, he published . 
at Lenz, ‘‘The Harmonies of the World,’’ in which he an- 
nounced his celebrated third Law, already given. It was 
dedicated to King James I of England, perhaps in the hope 
that he might thereby secure a new patron. And in due 
time an offer did come to him from that monarch, which, 
very wisely, he declined. In 1618 the three first books of 
his ‘‘Epitome of the Copernican Astronomy’’ appeared, 
the other three being delayed until 1622. This work, much 


98 Beacon Lights of Science 


to his alarm, was at once placed on the Index Expurga- 
torius by Pope Urban VIII. 

In 1622, through the persistent efforts of Ferdinand, part 
of the State’s indebtedness to him was paid, and funds se- 
eured for the publication of the Rudolphine Tables; but 
on account of the disturbed political conditions in Central 
Europe at the time, they did not appear until 1627. 
Shortly before their issue from the press Kepler received 
from the Duke of Friedland, an offer to take up his resi- 
dence at Sagan in Silesia. He accepted, arrived there with 
his family in 1629, was most cordially received, and given 
a professorship in the University of Rostock with a hand- 
some Salary, an assistant calculator, and a complete print- 
ing outfit. There were still some 8000 crowns due him from 
Ferdinand of Bohemia, and Kepler went to Ratisbon and 
endeavored to collect it, but without success. Depressed 
at his failure, and worn out with fatigue and his lifetime 
of struggle with inadequate means, he contracted a fever 
which, in his sixtieth year, brought to an end a most strenu- 
ous and troubled but honorable career. 

Kepler was a man of tall and rather spare physique and, 
without subserviency, of strong inclinations towards peace 
with all men. His temperament was genial and even jocu- 
lar, inclining him at times to conclusions on slender foun- 
dations. On the other hand, there was a degree of persist- 
ence and honesty in his make-up, which compelled him to 
re-examine all these, until he was satisfied of their truth; 
or to admit an error frankly as soon as it became clear that 
he had made one. A striking example of these character- 
istics was his announcement of an observation of a transit 
of Mercury which, by others, was declared to be the diseoy- 
ery of the now well-known belt of spots across the disk of 
the sun. When the latter was announced, Kepler immedi- 
ately and publicly admitted his error, and commended the 
other explanation of the observed phenomenon. His was 
a mind free from the taint of jealousy, and unobseured by 
pride of opinion. In the early years of his public career 
he was undoubtedly much under the influence of the astro- 
logical tendencies of the age, but by middle life he had 


The Sixteenth Century 99 


become thoroughly aware of their absurdity, though, un- 
like Galileo, he had no inclination to crusade against them. 
Having suffered from infancy with weak and defective eye 
sight, he was barred from attaining eminence as an observer 
of the celestial bodies. His great faculty was that of gen- 
eralization, and of drawing conclusions from the observa- 
tions of others; and these gifts, aided by a fine mathemati- 
cal equipment, and persistency, enabled him to discover the 
three laws of planetary motion that constitute his enduring 
fame. His mortal remains rest in the churchyard of St. 
Peters at Ratisbon, but their exact location are unknown, 
because the bronze tablet set over his grave was destroyed 
or displaced in one of the battles the city went through. 
But nearby, in the Botanical Gardens of the old city, a 
beautiful monumental temple was erected to his memory in 
1808, in which stands his bust in Carrara marble. 


HARVEY (1578-1657) 


PHYSIOLOGY 


WituiAm HARVEY was a native of Folkestone, England; 
and at the age of fourteen was sent to Cambridge Uni- 
versity. After five years of study there he was provided 
with the means for traveling, and made a journey through 
France, Germany and Italy. What he learned on this trip 
inclined him strongly to the medical art, in consequence of 
which he enrolled himself at the University of Padua in 
Italy which, at the time, held perhaps the highest rank 
among the European schools in law and surgery. Here, 
while attending the lectures of Fabricius, the celebrated 
anatomist and surgeon, he learned of the existence of valves 
in the veins, the purpose of which at the time was not 
understood. But he was greatly impressed. Upon his 
eraduation in 1602 he returned to England, and entered 
upon the practice of the profession in London, rapidly at- 
taining such eminence that in 1607 he was elected a fellow 
of the Royal College of Physicians, and in 1616 to its chair 
of anatomy and surgery. During the intervening years 


100 Beacon Lights of Science 


he made a specialty of the study of the veins, arteries and 
heart, and finally announced his great discovery of the 
circulation of the blood. Before his time it was of course 
well known that the blood was constantly in motion in the 
living animal, but, because the arteries were always found 
empty after death, it was supposed that they were a part 
of the respiratory system, and carried air only. 

Harvey’s theory at first met with great opposition, and 
even ridicule, but in a short time that passed, and he had 
the satisfaction while still living of witnessing the complete 
and unqualified acceptance of his discovery. In 1628 his 
work on the subject entitled ‘‘Exercitatio de Motu Cordis 
et Sanguinis in Animalibus’’ was published in Frankfort, 
Germany, in Latin, as was the custom of the day with all 
literary productions of moment, that being the one lan- 
guage which all educated people in Europe were supposed 
to be able to read. 

The commanding position his discovery won for him is 
shown by the fact that from 1632 to 1648 he was physician 
to the King (Charles I), and accompanied him at the battle 
of Edgehill, during which the Prince of Wales and the 
Duke of York were left in his care. In 1645 he was elected 
Warden of Merton College, Oxford. 

Harvey’s investigations in physiology and anatomy in- 
cluded other subjects in which he made valuable contribu- 
tions to knowledge, but none of these were fundamentally 
so important and far reaching as his great revelation of 
the mechanics of the body. In this the outstanding feature 
was the explanation of the operation of the valves in the 
veins which, being so constructed as to be capable of passing 
the blood in one direction only, compelled it to keep mov- 
ing onward. Without them it would never get back to the 
heart which, in its turn pumped it into the lungs where it 
experienced the rejuvenation of oxygenation. It was this 
question that so powerfully attracted his attention during 
his student days, and invited his continued investigation 
until the problem was solved. It is true that in his day 
oxygen was unknown, as well as carbon dioxide, so that 
the actual chemical reaction that occurred in the lungs 


The Sixteenth Century 101 


could not be understood, but even in his time there was a 
general concurrence among physicians that the act of 
breathing was one which in some way resulted in a puri- 
fication of the vapors and liquids of the body, for at its 
cessation at death decomposition was observed at once to 
begin. 


MERSENNE (1588-1648) 


PHYSICS 


THE birthplace of Marin Mersenne was at La Soultiére, 
France. He obtained his education at the College of La 
Fléche, where he met the mathematician, Descartes. The 
two became lifelong friends. Being a fine mathematician 
himself and also a lover of music, he naturally was at- 
tracted by the science of acoustics, and discovered the laws 
which express the dependence of the time of vibration of 
the strings of a musical instrument, upon the length, ten- 
sion and density of the string, and formulated his deduc- 
tions in what is known as Mersenne’s Law, as follows: 

The time of vibration varies directly as the length of the 
string and the square root of its density, and inversely as 
the square root of its tension. 

In 1611 he joined the association called the Minim Friars, 
an order of monks founded during the 15th century, whose 
vows pledged them to the observance of a perpetual Lenten 
dietary régime, corresponding to what at the present time 
would be approximately that of a vegetarian, plus occa- 
sional fish food. From 1614 to 1620 he was a teacher of the 
philosophy of the day. He then removed to Paris, where 
he passed the remainder of his life, devoting his time out- 
side of that required by his religious duties, to the study of 
mathematics and astronomy. He was the Parisian repre- 
sentative of Descartes when the latter was in Holland. He 
wrote and published several monographs on the phenomena 
observed in the production of musical sounds which, for 
his day and time, were notable productions. 

Acoustics was one of the earliest of the sciences to re- 


102 Beacon Lights of Scrvence 


ceive attention in modern times. Brooks Taylor in 1715 
and Daniel Bernouilli in 1755 deduced mathematically the 
laws of vibration of a stretched string which Mersenne had 
discovered experimentally a century before, while Chladni 
in 1637 exhibited the effects produced by the longitudinal 
and torsional vibrations of metallic bars and plates. Pois- 
son in 1829 was the first to investigate the laws of vibra- 
tions in membranes. In Rayleigh’s notable work entitled 
‘“Theory of Sound,’’ which was published about 1880, the 
subject was exhaustively investigated. 

But the ancients and the scholars of the Middle Ages 
were, experimentally at least, not without considerable 
knowledge of the subject. Music among all people has been 
the first of the arts to be developed. Pythagoras, the Greek 
(circa 600 B.c.), knew that two stretched strings of the 
same material, cross-section and density, would vibrate in 
harmony if their lengths were as one to two, as two to 
three, as three to four, ete., but was apparently unable to 
explain the phenomenon. It had also been known from 
remote ages among savages that an appreciable time was 
required for the transmission of sound through the air, and 
that it traveled more quickly through the water or the 
earth. But it was not’ until Chladni showed by his famous 
experiment of ringing a bell in a vacuum in a glass jar, 
that sound was due to vibrations set up in a suitable 
medium, and that no sound would arise if no medium for 
its transmission existed. In high altitudes, where the at- 
mosphere is thin, the crack of a pistol is an insignificant 
affair, and the human voice becomes little more than a 
whisper or squeak. 

The human ear is so constructed that vibrations less in 
number than 30 per second, or greater than 20,000 per sec- 
ond are inaudible. In the case of music as differentiated from 
mere noise, the limits are actually between 40 and 4000, 
the lower number producing the effect of the deepest bass 
notes, and the upper that of the highest treble. The speed 
of travel of sound through dry air in a normal condition is 
1077 feet per second; through water 4664 feet; through 
steel 16,217 feet, and through glass 17,875 feet. The denser 


The Sixteenth Century 108 


the medium (if also fairly elastic), the more rapidly will 
it earry sound. On the other hand hydrogen, the lightest 
and most tenuous of the elements, will transmit its vibra- 
tilons at the rate of over 4000 feet per second, which would 
seem to indicate that elasticity more than density was at 
the basis of the phenomenon. 


DESARGUES (1592-1662) 


MATHEMATICS 


GERARD DESARGUES was born at Lyons, France. Of his 
youth little is known, but in his early maturity he was ree- 
ognized as a distinguished engineer and architect, and a 
mathematician of unusual ability. To him and Pascal are 
accredited the foundation work in the science of descriptive 
geometry—popularly known as the art of perspective— 
which later was developed to a high degree by Descartes. 

In mathematical investigations he reached some conclu- 
sions which, in his day, were not accepted; or, at least, were 
not confirmed; but which, at the present time (human 
mental capacity or scope having meantime perceptibly in- 
creased) have become partially comprehensible, as the re- 
sult of the enlarged knowledge of the properties of those 
concepts called Space and Time. Three of these are as 
follows: 

1. That a straight line, if produced to infinity, becomes 
a curve, whose two ends will meet and unite. 

2. That parallel lines, if produced to infinity, will also 
meet and unite (or intersect). 

3. That a straight line and a circle may become identical, 
or constitute two varieties of the same thing. 

Such propositions to most of us, and even to many with 
a good mathematical equipment, are hard sayings, or even 
absurdities, yet to the mathematician of genius they may 
represent statements of real truths which are slowly in 
process of experimental confirmation and demonstration as 
the Universe becomes better understood. The work of 
Desargues can be properly appreciated only by those few 


104 Beacon Lnghts of Science 


individuals who, from time to time, arise from the common 
run of humanity, to whom pure mathematics is not only the 
queen of the sciences, but actually the only one capable of 
revealing absolute fact. Such geniuses are rare, but no 
matter how difficult their conclusions are to be understood, 
they are really of fundamental importance in the slow but 
steady advance of knowledge. We have at last reached the 
comprehension that in the affairs of the Cosmos there is 
no such thing as chance. Fixed and immutable law governs 
every phase of existence, from that of the infinitely small 
to that of the infinitely great. Effect follows cause with 
absolute fidelity and certainty. Appearances, the evidences 
of the-senses, and even the conclusions of logic may, at 
times, seem to indicate otherwise; but the trained scientist 
in the quest of Truth at the present day will at once reject 
these if, in the smallest degree, they appear to indicate 
exceptions to the reign of unchangeable law. Or, as an 
alternative, will suspect that the law, as theretofore enun- 
ciated, has been incorrectly stated. 


DESCARTES (1596-1650) 


MATHEMATICS 


RENE Descartes (Renatus Cartesius) was born at La 
Haye in France and was educated at the Jesuit college at 
La Fléche, where he exhibited special aptitudes in mathe- 
matics, the languages and astronomy. Upon the comple- 
tion of his courses there he became dissatisfied with much 
of the teachings he had received which, in accordance with 
the ideas of the times, consisted largely of the Aristotlean 
philosophy combined with the doctrines of orthodox the- 
ology as laid down by the fathers of the Church. To clear 
his mind of these he entered the army as a volunteer. After 
several years of active service he resigned in 1621 and de- 
voted the next eight years to travel, finally settling down 
in Holland in 1629 where, for the following twenty years, 
he devoted his life to giving expression in his writings to 
the conclusions he had reached. These, largely of a philo- 


The Sixteenth Century 105 


sophical nature, took the form of a conviction that, because 
he was able to think, it was logically legitimate to conclude 
that he existed as a distinct Personality, a conviction which 
he put concisely in the phrase, Cogito, ergo sum (I think, 
therefore I exist) ; this being in contrast with the mental 
attitude of the lower animals, who he regarded as uncon- 
scious automata. 

Descartes gave expression to opinions regarding the ma- 
terial and objective world which have borne good fruit in 
the labors of subsequent investigators. He was a mathe- 
matician of high order, and the inventor of that branch of 
analytical geometry which is known as the Cartesian, and 
which may be said to constitute the point of departure of 
modern mathematics. 

In 1649 he was invited by Queen Christina of Sweden to 
visit that country, and accepted gladly the opportunity 
to escape hostile eritics in Holland. But a few months 
after his arrival in Stockholm he died. 






4 
Mile aN \ ry 
Runt at 






a si 

















it t i 
‘eRe Ea 
, j 
a Vv ; \ 
i j 
ree : 4 a. 
ey ¢ 
™ en 5 
i ' Wil iy ‘ 4 
AV : i 
rani4 
. 
Muley: A ay nd 
' ( etd be ahh 
“a Aa) aa 8) Ak $ Polat Cath te ~ 1 ca erent aa ite Palen t 
: EAvtia 1 ee AO Vy u Lt at val ; vit k 
Hy Me Wan Lae Mev Le: Reve, 1 ray phi 
Beith 7 j j ' Teal Ou Shea se Ai i 4 vie sues aa rt 
Gee \ j yi} eh Vai ty ri , ‘ In 
. : U rs " r ) 7 
Pea at LAAT ‘ ¥en (aha Sed 
: ¢ ii \ 
Ti Lye a ‘ 
‘| i J i 
TD: we : t 
1 4 ; YA wey \, \ 
7 Y Lire! ' 
4 \ 
Pa, “ Ue gad é 
j 
j i . ; 
Te 4 A ' 
’ fy i A] Pee ea " a 
i MW \ a ae ‘hl 
} if re tA “ { ny 
by , varie ‘a 
i ry 
l i : 
ye j | 
‘A j ty 
a a 
a! t f 
4 mu { Wane 
t { 4 






aad 


le 


te nus ; | Y hi % erie ; pei oii) 2 aks aa my 


IV 
THE SEVENTEENTH CENTURY 


Historically this period was one of almost continuous war in 
Europe. At its beginning, Spain was the dominant nationality, but 
before its close had sunk to the status of a third-rate power. Eng- 
land, after a half-century of prosperity under Queen Elizabeth, was 
compelled to endure nearly a hundred years of troublous times, which 
culminated in the Cromwellian epoch. The Netherlands (Holland 
and Belgium), after throwing off the Spanish yoke and attaining 
freedom, were threatened with the growth of the power of France 
which, under Louis XIV began to dominate the continent in 1643. 
Germany, during the whole period, was little more than a collection 
of feeble states, each struggling for existence, for during the Thirty 
Years’ War its population had been reduced more than half. At the 
foundation of all these miseries were the bitter animosities between 
the Catholics and Mohammedans in Spain, and Catholics and Protes- 
tants elsewhere. 

Under such unfortunate political conditions it is a wonder that 
science survived. Yet it produced some remarkable men. In mathe- 
matics, Fermat, of the calculus of probabilities; and Newton, the 
formulator of the law of gravitation. In astronomy, Cassini, the 
discoverer of the satellites of Saturn, and Halley of cometary fame. 
In physics, Bradley the detector of the aberration of light; Guericke 
and Torricelli who demonstrated the weight of the atmosphere; and 
Roemer, the discoverer of the velocity of light. The work of De 
Jussieu, founder of botany, born at its close, was done in the 18th 
century. 

All these men were developers of basic discoveries or conceptions. 
They were foundation builders. Upon it their successors in the 
fields of science erected a lasting and remarkable structure. 


FERMAT (1601-1665) 


MATHEMATICS 


PIERRE DE FERMAT was a native of the village of Beau- 
mont-de-Lomagne in southern France. He was educated 
privately, but thoroughly, at home, and lived a quiet and 
retired life, devoting his time mainly to writings on his 
favorite subject—mathematics. In this branch of science 
his contributions to the advance of knowledge were very 
great, perhaps the most important being his ‘‘Commen- 
taries of Diophantus,’’ the father of algebra. 

By some—Laplace and Lagrange—he was regarded as 
the inventor of the Calculus, or at least, in his methods of 
numerical analysis, the first suggestor of the modern form 
of that branch of mathematics. 

To Fermat is generally ascribed the rise in importance 
of the theory of Probabilities. This subject at first would 
seem to be one quite outside of the domain of mathematics, 
which is properly regarded as the one exact science. Yet 
the contrary is true, as may be made clear by the follow- 
ing examples: 

Suppose ten horses are entered for a race, one of them 
being a light bay in color and the property of an acquain- 
tance. Assume no knowledge of the trotting capacities of 
any of them. What then, from our point of view, are the 
chanees that our friend’s horse will win? At first, it would 
seem to be simply as 1 to 10. But, the heat having been 
run, we learn that a bay has won, and on glancing over 
the list of entrants we find that six are so described. At 
once the probability is reduced to the proportion of 1 to 6. 
But immediately thereafter we learn that the winner was 
a light bay, and upon a re-inspection of the list we find that 
two are given that shade of color. The chances then are 


109 


110 Beacon Lights of Science 


mathematically even, or as 1 to 2. At last we learn the 
name of the winner and recognize it as that of the horse 
of our acquaintance. This reduces the chance to the ratio 
of 1 to 1, or to that of certainty. 

In a generalized way the theory is stated as follows: ‘‘If 
an event can occur in any one of a number of different ways 
equally likely to occur, the probabilities of its happening 
at all is the sum of the several probabilities of its happening 
in the several ways.’’ The probability of an event not 
happening is found by subtracting from unity (1) the 
figure representing the probability that it will happen. If 
A’s chance of hitting a target is one-third, and B’s chance 
one-sixth, the chance that both will miss is 1, less (14 plus ¥%), 
which is 4% Or, the probability of drawing at one trial 
a white ball from a bag containing two white and three 
black balls is 24, and the probability of drawing a black 
one is 3%. These several simple illustrations appear self- 
evident and hardly worth serious consideration, and espe- 
cially so as a department of mathematical research. Yet 
the deductions from first axiomatic principles may be, and 
are applied to complicated conditions in insurance of all 
kinds, to games of chance and to certain astronomical prob- 
lems with great advantage. In the last case consider a 
series of observations of a celestial phenomenon in which, 
from the nature of the ecase—known defects of telescopes, 
imperfection of vision, incapacity to fecord instantane- 
ously, etec.—absolute accuracy is admittedly impossible. 
Here the employment of the data of the theory of proba- 
bilities as worked out by the mathematicians, has enabled 
the astronomer to reach a conclusion which he is entitled 
to consider as most probably correct, or one in which the 
chance of error is so small as to be negligible. The method 
of obtaining this least error quantity is called the ‘‘method 
of least squares.’’ It was first developed by Legendre in 
1805, and later elaborated by Adrian and Gauss. 


The Seventeenth Century 111 


GUERICKE (1602-1686) 


PHYSICS 


OTTO VON GUERICKE was a native of Magdeburg, Ger- 
many. He was liberally educated in the schools, and after- 
wards by travel in Holland, England and France. In 
1646 he was elected burgomaster of his native town. About 
this time he became greatly interested in the experiments 
made a few years before by Galileo, Pascal and others, on 
the weight and pressure of the atmosphere, and in conse- 
quence initiated an attempt to produce a vacuum. 

His first effort was made with a stout wooden barrel, 
which he filled with water, and from which he then ex- 
hausted the water with an ordinary water pump. But he 
found that though the barrel would hold the liquid without 
leaking, it could not be made tight enough to exclude an 
inrush of air, while the water was in process of being taken 
out. 

His next attempt was made with a hollow copper globe, 
fitted at one place on its surface with an opening to which 
the suction of a water pump could be securely attached, 
and at another with a stopcock. Having filled the globe 
with water, attached his pump and started it in operation, 
he was much astonished on finding that after drawing out 
some of the water the only way in which he could extract 
the remainder was by letting in some air behind it, through 
the stopcock, through which it then passed with a whistling 
sound. Also, that after exhausting the water and closing 
the stopcock, his water pump would draw out the most of 
the air, as well as the water, until in fact the pump itself 
began to leak air, and the copper globe began to show signs 
of collapsing. To Guericke therefore belongs the honor of 
having put into operation the first air pump. 

Convinced now that he had made a discovery of impor- 
tance, and wishing to exhibit in a striking way the effect 
of atmospheric pressure, he built two stout hemispheres 
of brass, each about a foot in diameter, which fitted to- 
gether accurately on their flanged edges, and provided one 


112 Beacon Lights of Science 


of them with a stopcock, and the other with a valved open- 
ing to which his pump could be connected. Each hemis- 
phere also had at its pole a strong ring, to which the harness 
of a team of horses could be attached. 

With this apparatus he appeared by request before the 
emperor Ferdinand III at Ratisbon, and operated it with 
great success. He first showed clearly that, if the stopcock 
was left open, the two hemispheres would fall apart, even 
when the flanged edges were heavily greased. But when 
the cock was closed, and the air pumped out, the two teams 
of horses provided for the experiment, and working in op- 
position to each other, were unable to separate them. 

This famous experiment—which is known in the records 
as that of the ‘‘Magdeburg Hemispheres,’’ created the 
greatest interest throughout intellectual Europe, and 
started a movement in physical investigations which led 
before long to other discoveries equally important and as- 
tonishing. 

Von Guericke is also remembered as the first investigator 
to demonsrate that sound is the effect produced on the 
mechanism of the ear by vibrations of the air. This was 
accomplished by suspending a bell in an airtight glass ves- 
sel and in such a way that it could be rung from the out- 
side of it. When the air was exhausted by a pump, and the 
ringing mechanism set in motion, the clapper could be seen 
plainly to be striking the rim of the bell, but no sound re- 
sulted. However, when the bell was so hung as to come in 
contact with the side of the glass container, so that the 
vibrations could be communicated to the glass, and then 
rung, it became at once audible. 


TORRICELLI (1608-1647) 


PHYSICS 


EVANGELISTA TORRICELLI was a native of Piancaldoli, a 
small town near Florence, Italy, and having studied mathe- 
matics and physics at Rome, under a favorite disciple of 
Galileo, he atracted the attention of the latter—now in his 
old age and blind—and was invited to join him at his 


The Seventeenth Century 113 


Florentine home and become his assistant and secretary or 
amanuensis. Upon the death of the philosopher, Torricelli 
succeeded to his professorship in the University of Flor- 
ence, which position he held until his death at the early 
age of 39 years. 

His principal contribution to science was the demonstra- 
tion of the weight of the atmosphere by means of the mer- 
curial barometer, of which he was the inventor. As far 
back as the days of the old Greek philosophers, Plato and 
Aristotle, it was known that the atmosphere possessed that 
quality, even when in a quiescent state, because it exhibited 
power when in motion; but the amount of its weight was 
unknown. Both Galileo and Torricelli were aware of the 
fact that, by suction, water could be lifted in a tube to the 
height of 32 to 33 feet, and had deduced from it that the 
pressure exerted by the atmosphere on the surface of the 
water in a well, must be in the vicinity of 15 pounds to the 
Square inch; and the former had expressed the opinion that 
the principle, if accurately demonstrated, might be use- 
fully employed in measuring the variations in this pres- 
sure due to storms, and to altitudes above sea level. But 
the mechanical difficulties connected with the manufacture 
and installation of a glass tube of that length, were not 
easy to overcome at the time. 

In the year following Galileo’s death Torricelli took up 
the problem again, and bethought him of the idea of sub- 
stituting mercury for water. Knowing that the weight of 
the metal was thirteen to fourteen times that of an equal 
volume of water, he reasoned that a tube one-thirteenth 
the length of that which would be required if water was 
employed, or, about 30 inches, would answer when using 
mercury. Such a tube of glass with a fairly uniform bore 
was, by then, within the capacity of the manufacturers. 
Accordingly he procured one about a yard in length, closed 
it at one end, and filled it with the metal. Then, inverting 
it in a vessel filled with liquid metal, he had the satisfaction 
of seeing the column sink down to a height of about 30 
inches as expected, leaving a vacancy above it in the tube, 
which became known as the Torricellian vacuum. 


114 Beacon LInghts of Science 


On the foundation of this simple principle, modified to 
meet the various demands made upon it as an instrument 
of precision, all the varieties of the modern mercurial ba- 
rometer are based, which are used not only for ascertaining 
the changes in weight of the ocean of air surrounding the 
globe, but also the elastic pressure of all kinds of gases. 

Torricelli is also thought to have been one of the first to 
work out correctly the principle of the simple microscope, 
and to construct one that would yield practical results. 
His principle was developed by Antony van Leeuwenhoek 
of Holland (1632-1723), who is said to have made over two 
hundred very efficient instruments of one lens only. For 
the modern high power microscope, however, the world 
had to wait until the first quarter of the 19th century 
(1812-1827), during which period the art of lens grinding 
and polishing was highly advanced, and makers of the in- 
strument learned how to combine them, so as to correct 
almost perfectly their chromatic effect on light. 


PASCAL (1623-1662) 


MATHEMATICS 


BLAISE PAscAL was born at Clermont-Ferrand in France, 
of a family of the old nobility who for generations had been 
Prominent in government affairs. He displayed unusual 
mathematical capacity in his youth, and received his edu- 
cation mainly under private tutors at home. In 1631 his 
father removed the family to Paris where the boy, as he 
grew up, became deeply interested in physics. At the time 
this science was in its infancy, and was slowly developing 
along lines which called for a knowledge of the higher 
mathematics for solution of many of the problems that it 
was presenting. 

In 1651 his father died, and shortly thereafter a sister 
named Jacqueline, to whom he was deeply attached, en- 
tered the Jansenist convent at Port Royal. For three years 
the young man remained practically alone at Paris. But 
finding life insupportable without her companionship, he 


The Seventeenth Century 115 


also became a member of the order. To understand the 
effect of this step on his subsequent life, it is necessary to 
know something of the conceptions for which the society 
stood. 

Jansenism was the name given to one of the many so- 
called schisms that have broken out from time to time 
throughout the history of the Church of Rome. The ques- 
tions at issue were mainly those of the ‘‘efficacy of divine 
erace,’’ and the meaning and limits of the doctrine of ‘‘free 
will.’’ Over those abstruse problems—as might naturally 
have been expected—hbitter controversies arose, which 
lasted through nearly a century, and out of which of course 
no settled conclusions were ever reached. Pascal’s appar- 
ent mental attitude in joining the order was not so much 
to espouse the cause for which it stood, as the desire, in 
the quiet and seclusion of a monastic life, to labor for the 
progress of science, as the duty of a man to whom had been 
given an inquiring mind. Nevertheless, he seems to have 
held the opinion that mental and moral certitude could only 
be found in revelation, that is, in the teachings of the Scrip- 
tures. 

The most powerful opponents of Jansenism were the 
Jesuits. With them, but anonymously, and rather at first 
by accident than design, he entered into a prolonged con- 
troversy. As it advanced it became, on his side at least, 
intensely bitter; revealing his real attiude as that of the 
protestant against the casuistry and illogicality of the theo- 
logical discussions so prevalent in Europe during the 16th 
and 17th centuries. These writings, which were collected 
and published after his death, have value now only as lit- 
erary curiosities, and as examples of a beautiful and in- 
cisive style. 

In scientific matters Pascal, in a treatise entitled ‘‘New 
Experiments on the Vacuum,’’ demonstrated that the con- 
clusions reached by Torricelli a few years previously as to 
the weight of the atmosphere, were correct. In one of these 
he substituted wine for water in the barometrical tube, and 
in another had it (filled with mereury), carried to the sum- 
mit of the French mountain called ‘‘ Puy-de-Déme,’’ which 


116 Beacon Lights of Science 


rises to an altitude of 4086 feet, and where, as he expected, 
the pressure of the air was so much less, that the column 
of mereury it would Sustain was considerably shorter than 
at sea level. Thus was at last completely solved the ancient 
puzzle as to why water can be lifted in a pipe by suction, 
but only to a maximum height of 32 to 33 feet. 

Although a mathematician of unusual ability, Pascal 
took little pleasure in the exercise of the talent during the 
mature years of his life. In his early youth he published 
an essay on the ‘‘Geometry of the Conic Sections’’ which 
ranked high in its time; and in 1685 another one descrip- 
tive of his device known as ‘‘Pascal’s Triangle,’’ which 
solved graphically a rather complicated mathematical prob- 
lem. He also took part with Descartes in extending the 
scope of the ‘‘ Theory of Probabilities.’ But his heart was 
not in such work. Nor, towards the end, was it in the re- 
ligious controversies to which he gave so much of his ma- 
ture energies. Towards the latter part of his brief and 
troubled life he became an anchorite and a pessimist, un- 
comforted even by the beliefs on which he had placed so 
much reliance in his youth. 


BOYLE (1627-1691) 


CHEMISTRY 


RosBert BoyvLE was born at Waterford, Ireland. After 
passing through Eton College in England he traveled on 
the continent for six years when, by the death of his father, 
he came into possession of the family estate; the Manor of 
Stallbridge in Dorsetshire, England. Here he resided until 
1654, when he moved to Oxford, and became one of the 
first members of that social group of scientific men which, 
at that time, held private and informal meetings at London 
and Oxford, and constituted the nucleus of the organiza- 
tion later known as the Royal Society. 

Boyle took a very prominent part in laying the founda- 
tions of the coming science of physics, by experiments and 
investigations in pneumatics and allied subjects. His chief 


The Seventeenth Century 117 


contribution was the enunciation of what has since been 
ealled the ‘‘Law of Boyle and Mariotte,’’ because discov- 
ered independently by the two. It may be stated as follows: 
‘““When a gas is at a constant temperature, the product of 
the pressure and volume of a given mass of it remains con- 
stant.’’ Or, as follows: ‘‘If the temperature of a gas is 
kept constant, and its volume changes, the resulting pres- 
sure and density are such that one is proportional to the 
other.”’ 

Investigation has shown that this law is only approxi- 
mately correct in the case of high pressures, but it answered 
all purposes in Boyle’s day, and for a century afterwards. 
Its inexactitude simply means that at high pressures gases 
are proportionately less compressible than they are at low 
pressures, a conclusion that might easily have been foreseen 
if, at the time the law was enunciated, the molecular 
nature of matter had been understood. For, as the mole- 
cules of a gas are brought by pressure into closer proximity 
with each other, a point is finally reached when mutual 
attraction between them becomes strong enough to effect 
a reduction of outward pressure. Ultimately, as we now 
know, if increase of external pressure continues, combined 
with gradual lowering of the temperature, a ‘‘critical 
point’’ is finally reached, at which the gas becomes a liquid, 
and incapable of exerting any outward pressure except that 
due to its weight. 

The gaseous, being the simplest form or condition in 
which matter occurs in nature so far as at present known, 
is not only the easiest to investigate but, its laws when 
in that condition having been discovered, those which gov- 
ern it in the liquid and solid state, and in that fourth state 
known as the colloidal—first recognized by Graham about 
1845—and intermediate between the liquid and solid con- 
dition, can more readily be inferred. For these reasons, 
as soon as the common elementary gases (oxygen, hydro- 
gen, nitrogen and chlorine) were discovered and investi- 
gated, and the composition of the atmosphere made clear, 
a sure foundation was laid upon which the structure of the 
science of chemistry could be raised. 


118 Beacon Lights of Science 


In gases under normal conditions, such as is meant when 
speaking of the atmosphere as ‘‘free air,’’ a state in which 
it is subject to no pressure or force beyond that of the at- 
traction of gravitation, the molecules of which it is com- 
posed are separated from each other by spaces or voids so 
large, as compared with their size, that their mutual at- 
traction—which constitutes the property called cohesion— 
is negligible, and consequently their movements among 
themselves are unlimited in complexity, and incessant; and 
the pressure they are capable of exerting against the sides 
of any vessel in which they may be confined, is that due 
only to the weight of the volume so enclosed which, itself, 
is solely the effect of the gravitational pull of the earth 
there. A vessel of thin glass filled with air at sea level and 
sealed, and then taken to a high altitude, will ultimately 
burst; first, because the surrounding free air being itself 
farther away from the earth, and so less under the influ- 
ence of its attraction, has lost in density or, as is said, has 
become thinner, and so can exert less pressure per square 
inch on the outside of the walls of the vessel; and second, 
because the imprisoned air, being at a greater distance than 
before from the center of the earth, is less influenced by it: 
gravitational pull, and consequently its molecules are more 
eager to separate from each other, and so press more 
urgently on its interior walls. 


CASSINI (1625-1712) 


ASTRONOMY 


GIOVANNI DoMINICO CASSINI was a native of Perinaldo, 
Italy; and after receiving an excellent education became 
professor of astronomy at the University of Bologna, where 
he acquired such a reputation as an observer of celestial 
phenomena that he was offered the position of director of 
the observatory at Paris, where he remained for the bal- 
ance of his active life. At his death the office passed to 
his son Jacques who, in turn, yielded it to his son Jean 
Dominique. Thus, for a period of nearly a century the 


The Seventeenth Century 119 


noted observatory was under the guidance of one family, 
all of whom greatly distinguished themselves in their work. 
To the oldest of the three, however, is due by far the larg- 
est number of important discoveries made and conclusions 
reached. Among the most notable of these were the de- 
termination of the motions of the satellites of Jupiter; the 
discovery of four of Saturn’s family and the ascertain- 
ment of their periods of revolution; the rotational periods 
of Jupiter, Mars and Venus; the first systematic study of 
the zodiacal light; a close approximation of the parallax 
of the sun; a table of refractions; a complete theory of 
the phenomenon called the libration of the moon; a revised 
calculation of the obliquity of the ecliptic, making it 23° 
28’ 42” instead of 23.5 as previously determined, and an 
amended figure of 0.017 for the eccentricity of the earth’s 
orbit which, by Kepler, had been assumed at 0.018. He is 
also remembered for having advanced the theory that the 
figure of the earth is not that of a sphere but of an oblate 
spheroid, flattened at the poles and bulging at the equator ; 
the equatorial diameter being 7926 miles and the polar 
7900 miles. Finally he was the discoverer or designer of 
the geometrical figure known as the Cassinian Oval, which 
may be described as a symmetrical bi-circular curve caused 
by the movement of a point the product of whose distances 
from two fixed points is a constant. 


MALPIGHI (1628-1694) 


ANATOMY 


MarcELLO MALPIGHI was a native of Crevaleuore in Italy. 
He studied at the University of Bologna, was given his doc- 
tor’s degree in 1653, and three years later became profes- 
sor there, attaining a high reputation as a popular lecturer. 
In 1662 he was elected to the chair of anatomy at the Uni- 
versity of Messina, where he remained until 1691, when 
he was called to Rome to occupy the position of personal 
physician to the Pope (Innocent XII). A few years later 
he died very suddenly of apoplexy. 


120 Beacon Inghts of Science 


Malpighi was a tireless investigator, and deeply in love 
with his profession which, at the time, was rapidly emerg- 
ing from the ignorant empiricism of its past, and becoming 
an art based on a more extended knowledge of the consti- 
tution of the body, and the duty of its organs., He took 
a prominent part in the enlargement of this knowledge, 
dissecting animals and plants, as well as human bodies. 
He discovered the function of leaves in vegetation (as 
breathing organs) ; described the development of the chick 
in the egg, and the changes through which the silkworm 
passed in building its cocoon; and—what perhaps was his 
greatest achievement—demonstrated by the aid of the 
microscope the capillary circulation of the blood in the 
lungs. It could hardly be expected that all the conclusions 
of this celebrated morphologist would be confirmed by later 
investigations, for in his day the microscope was a most 
erude instrument. But a remarkably large proportion of 
them have been. One of the most interesting of the dis- 
coveries credited to him, was that of the spiral form of 
the muscles which control the movements of the heart. 

His death at the early age of 66 was directly due to his 
intense devotion to research in his line. So engrossed 
would he become in a dissection that food and sleep were 
neglected, and eyesight strained beyond all reason. He was 
a direct victim to overwork. He was the author of a num- 
ber of valuable monographs of which the two most notable 
were entitled ‘‘Observationes Anatomacae’’ (1661), and 
‘‘Hpistolae Anatomacae’’ (1665). In the latter he reported 
his discovery of the third and innermost layer of the hu- 
man skin, which has ever since been known technically as 
the ‘‘Rete Malpighi.’’ It is the one which contains the 
pigment that determines the color of the individual. The 
two layers that cover it are nearly transparent. 


HUYGENS (1629-1695) 


PHYSICS 


CHRISTIAN HvuyGENsS was the son of Constantine Huygens 
van Zuylichhem, a noted Dutch writer, and Counselor to 


The Seventeenth Century 121 


the Prinees of Holland, and was born at The Hague on 
April 14, 1629. During his adolescence he received a thor- 
ough education in fundamentals under private tutors, and 
at the age of 16 was sent to the University of Leyden to 
specialize in law and mathematics. Becoming unusually 
proficient in the latter, he published in his 22nd year 
(1651), his first work, entitled ‘‘Theorems on the Quadra- 
ture of the Hyperbola,’’ a very creditable study for his 
age and time. In 1656, with a telescope of his own manu- 
facture, he discovered the first of the nine satellites of 
Saturn, and in the following year he introduced the prin- 
ciple of the pendulum in the art of clock making, and some 
years later, the spiral spring in the manufacture of watches. 
In 1659 he published his ‘‘System of Saturn’? in which a 
complete description of the rings was given, as the result 
of observations made through a telescope of 22 feet focal 
length. In the following year, at the invitation of Minister 
Solbert of France, he went to Paris, was given quarters for 
his studies in the Royal Library, and made a member of 
the Academy. In 1663, while on a visit to England, he was 
elected a Fellow of the Royal Society of London. Return- 
ing to Paris in 1665 he made it his home until 1681; when, 
recognizing that the disposition towards the persecution of 
Protestants in that country was growing, and anticipating 
the revocation of the Edict of Nantes (which gave them 
protection), he returned to Holland, and remained there 
during the balance of his life. 

While living in France he demonstrated the laws under 
which force is transmitted from one body to another 
through impact; wrote and published a treatise on the laws 
of the refraction of light through transparent and trans- 
lucent material; a monograph on the nature of the cycloidal 
curve, and another on centrifugal force as exhibited in 
circular motion around a fixed center or axis. Finally, in 
1673, he gave to the world his great work entitled ‘‘ Horo- 
logium Oscillatorium,’’ in which the principle of the pen- 
dulum was exhaustively studied and applied, in marking 
divisions of time, and in the determination of latitudes. 

On his return to his native land he undertook the con- 


122 Beacon Lights of Science 


struction of a planetarium, and also engaged in the manu- 
facture—but for his own use only—of telescopes of great 
size, one of which had a foeal length of 210 feet. In 1690 
he published a treatise on the ‘‘Cause of Gravity’’ and an- 
other on ‘‘Light.’’ In the latter he suggested the undula- 
tory explanation, which is now universally held. 

His death occurred in 1695. Three years thereafter his 
‘‘Cosmotheoros’’ was published. This was a highly specu- 
lative and rather fanciful monograph, in which the sugges- 
tion was advanced that some, or perhaps all, of the planets 
of the solar system were inhabited, either by humans like 
ourselves, or by intelligent creatures of a similar kind, with 
bodies modified to conform to the special conditions of their 
environment. 

Huygens was an aristocrat of the best character and 
kind, and when the estates and titles of his father passed 
to him in 1687 he was able to devote his energies to experi- 
mentation and study along those lines that interested him 
most highly, and used the opportunity well. He never 
married. His disposition was that of a quiet and some- 
what reserved gentleman, with the inclination to use his 
own hands in experimentation, and equipped with a mind 
eapable of interpreting results with much acumen. To- 
wards his last years he became more speculative, as was 
displayed in his posthumous work, and there are reasons 
for thinking that he recognized the doubtful character of 
its conclusions. In several of his monographs he approached 
the vision that later blossomed in the mind of Newton. 


LEEUWENHOEK (1632-1723) 


MICROSCOPY 


ANTONIUS VAN LEEUWENHOEK was a native of the city 
of Delft, in Holland. He received from his father an 
ordinary business education, and at his death an inheri- 
tance that made him financially independent. Follow- 
ing a natural inclination he engaged in the manufacture 
of lenses, and from that became interested in the phenom- 


The Seventeenth Century 123 


ena of optics. This led ultimately to the discovery of the 
principles underlying the construction of telescopes and 
microscopes. Being more interested in the revelation of the 
latter than of the former, and an expert workman in the art 
of lens making, he produced remarkably fine microscopes 
for his time, and became such an ardent explorer in the 
field so opened for research, that he is rightly regarded as 
the founder of the science of microscopy. His individual 
discoveries in this department of knowledge were very 
numerous. Among them of great importance, were the 
identification of the red corpuscles in the blood, the stria- 
tion of the muscle fibers, and the verification of Harvey’s 
theory of the circulation of the blood, by showing its pas- 
sage from the arteries to the veins by the connecting capil- 
laries. He was also the first discoverer of many minute 
forms of life, such as hydra, infusoria, rotifers and sperma- 
tozoa. His studies in insect life led him to the discovery 
ef the parthenogenetic reproduction of the aphides (plant 
lice), which disproved many supposed eases of spontaneous 
generation. Huis researches, though not always conducted 
along strictly systematic and scientific lines, were noted for 
their character of conscientious accuracy, and have been 
of great service in the development later of the study of 
minute things. 

Long before the days of Leeuwenhoek it was known that 
lens-shaped pieces of transparent material—glass or crys- 
tals—and globules of water or other liquids, had the power 
of apparently enlarging the size of objects too minute to 
be distinguished in detail by the naked eye. In fact, a 
plano-convex lens of quartz less than two-tenths of an inch 
in thickness and one and four-tenths in diameter, with a 
focal length of four inches, was found by Ledyard in exca- 
vating the ruins of Nineveh, and is now in the British Mu- 
seum. This probably was employed as an aid in executing 
the delicate engraving found on many of the seals and gems 
of the period, or possibly as a burning glass. For the 
capacity of lenses to collect and concentrate the heat rays 
of the sun, and start a fire in dry tinder, was well known 
to the Greeks and probably to the Egyptians and Meso- 


124 Beacon Lights of Scrence 


potamian people. But all knowledge on the subject, except 
in connection with the manufacture of spectacles, seems to 
have perished in Europe with the fall of the Roman Em- 
pire; and not until the latter part of the Middle Ages was 
the art recovered there. In 1590 a spectacle maker of Mid- 
dleburg, Holland, named Janssen, is said to have con- 
structed the first instrument with two lenses, the object 
glass and the eye glass. It was nearly six feet long. Later, 
Divini in 1568, Robert Hook in 1675 and Campani in 1686 
brought out important modifications, but the serious diffi- 
culties due to the high aberration of light in passing 
through lenses of short focal length, made the use of their 
instruments very unsatisfactory. It was not until the prin- 
ciple of achromatic lenses was discovered in 1757 that this 
could be partially overcome by their use in the objective. 
In 1828 several pair of double lenses was first employed by 
makers, each consisting of a plano-convex of flint glass of 
high dispersive power, combined with a double convex of 
crown glass of low dispersion. This corrected aberration 
admirably. Since then, the miscroscope has been further 
improved, not only in the matter of lenses, but in focusing 
devices, the introduction of the cover glass over the objec- 
tive, the reflecting mirror and the use of a glass made on 
principles especially suitable for microscopic research. 


HOOKE (1635-1703) 


PHYSICS 


RoBeRT HooKE was born in the Isle of Wight, in Eng- 
land, and was educated at Westminster School in London, 
and at Oxford. In 1664 he became an instructor in geom- 
etry at Graham College, London. In 1666 occurred the 
great fire in that city, which followed the great plague of 
the year before, in which nearly 100,000 of its citizens died, 
corresponding to about one-quarter of its population at the 
time. In the fire 1300 houses and 19 churches were burned. 
When at last its progress was stayed, Hooke tendered to 
the authorities—together with a model—a very well 


The Seventeenth Century 125 


thought out plan for its rebuilding, which subsequent 
events clearly demonstrated should have been followed. 
But though he was appointed city engineer in 1667 his 
design was not adopted. From 1667 to 1682 he acted as 
secretary of the Royal Society. The last twenty years of 
his life were devoted to research, and to his many inven- 
tions. Hooke was a man of unusual ability, in fact, a 
genius. But unfortunately with this was coupled a tem- 
perament so irritable, and at times peevish, that he was 
constantly in trouble with associates, and even with inti- 
mates. Nevertheless, his acuteness of perception was so 
marked a characteristic, that he reached many important 
conclusions in science for which he should be accorded the 
eredit. In 1665, in collaboration with Boyle, they per- 
fected an air pump which was a vast improvement on the 
one designed and successfully operated the year before by 
Von Guericke in his classical experiments on the vacuum in 
Germany. 

Hooke was really the first physicist to point out that the 
problems of planetary motion were purely matters of me- 
chanics, and should be studied from that point of view, 
thus plainly intimating that forces of one or more kinds— 
as then’ unknown—were the agencies which compelled the 
heavenly bodies to travel through the paths that observa- 
tion showed they followed; thus anticipating the work of 
Newton. But he failed to develop the conception mathe- 
matically. More than a century and a half before Rum- 
ford demonstrated the identity of heat and motion, Hooke 
derided the opinion of his day that it was a fluid, or any 
kind of matter, and even suggested that it might be ‘‘an 
effect of motion.’’ 

In his book entitled ‘‘Micrographia,’’ which was pub- 
lished by the Royal Society in 1665, in describing his work 
with the newly invented microscope, and which with char- 
acteristic ingenuity he had improved by compounding its 
lenses, he clearly described what he called the ‘‘little boxes 
or cells’’ that were revealed in the leaves of plants under 
observation, and which have since become to the biologists 
of the present day the units of organized life. If the achro- 


22 


126 Beacon Lights of Science 


matic lens (which was only devised a century later) had 
been available to him, no doubt he would have discovered 
the minute particle of protoplasm that these ‘‘little boxes’’ 
contained, and detected their motion. 

He must be credited also with some views on the sub- 
ject of fossils that were at least of a prophetic nature. In 
his day all such objects, when found, were gravely discussed 
as evidences of the Noachian Deluge. But when whole 
formations of chalk were shown by the microscope to con- 
sist entirely of the shells of minute organisms, Hooke was 
among the first to declare boldly that some other and more 
reasonable explanation of their origin must be found, and 
even went so far as to express the opinion that it should 
be possible, through a study of the many different kinds 
of fossils then known, to arrive approximately at the rela- 
tive ages of the rocks in which they occurred; a conclusion 
which has since been entirely confirmed. 

To Hooke we owe the invention in 1658 of the balance 
wheel, which differentiates the watch from the clock, and 
made the former a possibility. A world without this mar- 
velous little machine would be a difficult one to imagine. 


NEWTON (1642-1727) 


PHYSICS 


Tue celebrated English scientist, Isaac Newton, was the 
son of a small freehold farmer, in Woolsthorpe in Lanea- 
shire, England. His early education was acquired at the 
grammar school at Grantham, near by, and at the age of 
19 he entered Cambridge University. His inclinations were 
so distinctly mathematical, that before he had completed 
his course there he had not only mastered all that the uni- 
versity could give him in that science, but had gone beyond 
it, by extending the applications and usefulness of the Bi- 
nomial Theorem, the method of Tangents, and that of 
Fluxions, which latter was the name then given to what 
is now understood as the Integral Calculus. It was in 1665 
—according to the commonly accepted story, for which 


The Seventeenth Century 127 


there is much foundation of authority—when his attention 
was directed, as he was sitting under an apple tree in his 
father’s orchard at Woolsthorpe, to the fall of the fruit— 
and to speculations concerning the cause of it. Ever since 
the publication of the theories of Copernicus as to the 
movements of the heavenly bodies (if not centuries before 
among the Greek philosophers) the existence of a force of 
some kind had been postulated, to account for the move- 
ments of the planets in space, but it was left to Newton, 
not to explain it, but to state the laws under which it oper- 
ated. For this task his exceptional mathematical equip- 
ment pre-eminently fitted him, but it was not until 1687, 
over twenty years after he began to study the problem, that 
he was able to announce the ‘‘Law’’ upon which his im- 
perishable fame rests. In his early attempts at its solution, 
he was defeated by the fact that he employed a figure for 
the radius of the earth, which was derived from an errone- 
ous valuation of the length of a degree of longitude. This 
figure produced only an approximate verification of the 
hypothesis he had conceived, and after going over his eal- 
culations with the greatest care, and finding no material 
mistake in them, he abandoned the quest temporarily, and 
turned his attention to other matters; investigating the na- 
ture of light, and the details of the construction of tele- 
scopes. In 1667, having procured a glass prism of good 
quality, and employed it in the separation of a beam of 
sunlight into the primary colors, he reached the obvious 
conclusion that the degree of dispersion varied for each 
color. This enabled him to account for the lack of defini- 
tion of the image formed by the object glass of a refracting 
telescope. But, after making one experiment in the effort 
to correct the difficulty, and getting no result, he hastily 
reached the conclusion that the dispersive power of lenses 
was invariably proportional to their refractive power, and 
that in consequence the production of a perfect image of a 
distant object was an impossibility, with that kind of an 
instrument. It was thus natural that he should abandon 
the refracting telescope, and turn his attention to the re- 
flecting variety which was then unknown. The instru- 


128 Beacon Lights of Science 


ment he constructed proved serviceable, and with it he 
made a careful study of Saturn and its satellites. Sixty 
years later the first achromatic lens was successfully per- 
fected by Chester More Hull. 

In 1672 he was elected a member of the Royal Society 
of London, and on the occasion of his installation read his 
famous paper on ‘‘The New Theory of Light and Color,”’ 
in which he showed that sunlight is a commingling in defi- 
nite proportions of all the primary colors and their inter- 
mediates, and in 1675 another paper on the same subject, 
calling attention to the phenomenon known as the Newton 
Rings. In connection with the latter he formulated the 
emission theory of light, on the foundation of calculations 
made some years before by Descartes. At the basis of this 
was the hypothesis that light consisted of material cor- 
puscles, emitted by the luminous body. Henee, it is known 
as the ‘‘corpuscular’’ theory. It was universally accepted 
as a correct explanation, until superseded by the undula- 
tory theory about 1815, which had been suggested first by 
Huygens in 1690. 

In 1679 a new and much more accurate determination 
of the earth’s diameter became available, and shortly there- 
after Newton resumed his studies on gravitation. In 1684 
his conclusions were confidentially given to Halley, the 
astronomer (after whom Halley’s comet is named). An 
outline of them was first embodied in a monograph en- 
titled ‘‘De Motu Corporum,’’ but under the advice of Hal- 
ley, he substituted for it a much more elaborate paper, 
which was entitled ‘‘Philosophiae Naturalis Principia 
Mathematica,’’* now universally referred to as the ‘‘ Prin- 
cipia,’’ and gave it to the world in 1687. 

This production, perhaps the most notable scientific work 
which the mind of man had so far brought forth, was in 
three parts, two of which were devoted to the subject of 
Motion in general, and its laws, while the third is confined 
to the movements of the members of the solar system. At 


1 The Mathematical Principles of Natural Philosophy. 


The Seventeenth Century 129 


the foundation of the discourse the universal law of gravi- 
tation was given as follows: 


‘‘Kvery particle of matter attracts every other particle, with a 
force directly proportional to their masses, and inversely proportional 
to the square of the distances between them.”’’ 


Since 1669 Newton had occupied the Leucanian chair at 
Cambridge, and had taken an active part in defending the 
rights of the university against the encroachments of King 
James II, who, being a Catholic, was not in sympathy with 
the liberal atmosphere of the great institution. The ability 
the astronomer had displayed in the contest led to his elec- 
tion to the Convention Parliament, in which he served from 
early in 1689 to its dissolution in 1690. In 1689 he was 
appointed Warden of the Royal Mint, and in 1699 was ad- 
vanced to that of its Master, which office he retained during 
the balance of his life. In 1701 he was again the chosen 
reresentative of the university in Parliament, and in 1703 
was elected President of the Royal Society, a position which 
he also held until his death, being re-elected for twenty- 
four consecutive terms of a year each. During this nearly 
quarter of a century of political and scientific activities he 
made it an invariable rule to subordinate his studies to his 
public duties, and yet found time to do much towards the 
advance of science. One of his important works during the 
period was the superintendence of the compilation and pub- 
lication of the ‘‘Greenwich Observations. ”’ 

His death occurred on March 20, 1727, at the ripe age 
of 85. His remains rest in Westminster Abbey, where a 
handsome monument was erected to his memory in 1731. 
At his death a cast was taken of his face, and from this a 
superb full-length statue was made by Roubillac, which 
stands in the ante-chapel of Trinity College at Cambridge. 
He was knighted by Queen Anne in 1705, 

In person Newton was a man of medium height and ro- 
bust build, inclining towards corpulency in his later years, 
though a light and almost spare eater. In his prime his 
countenance, which was finely and symmetrically cut, ex- 
pressed thoughtfulness and mental repose. In manner he 


130 Beacon Lights of Science 


was affable and modest, rather reserved and dignified, but 
without the least implication of hauteur. In speech he was 
invariably moderate, even when giving expression to views 
strongly held. He never married. From early manhood he 
was always in comfortable financial circumstanees, and left 
an estate estimated at about $150,000, which meant great 
affluence for his day. This was distributed by his will 
among his brothers and sisters and their children, with 
whom during life he was very liberal. In the matter of 
religion he was classed by his contemporaries as a devout 
and earnest man. Yet, though a member of the Anglican 
church, he declined to take orders (which were offered) in 
it, and evidently considered himself at liberty to stay in 
its fold without being expected to endorse all the tenets 
of its faith. 

At the age of 60 to 65 his health began to fail, and while 
he did not allow the circumstance to interfere with his 
public duties, he began to abandon science as a field of 
thought, and to turn his mind to speculations regarding the 
future. Having a profound reverence for the Scriptures, 
these took the form of endeavoring to fathom the mysteri- 
ous saying of the books of Daniel and of the Revelations of 
St. John, about which he wrote rather voluminously, but 
apparently with no intent of publication. Reference was 
made to some of these studies in letters to friends. As a 
result the impression went abroad that his mind was fail- 
ing. There can be no doubt that during the last decade of 
his life his mental attitude was changing, for the disease 
from which he died (gout and allied distempers) invariably 
causes that effect. Nevertheless, barring short lapses of 
memory, he preserved his faculties to the end; though dur- 
ing the last year or two he suffered severely at times. In 
1733, six years after his death, his scriptural studies were 
published under the title of ‘‘Observations on the Prophe- 
sies of Daniel and of the Book of Revelations.’’ They are 
not regarded as possessing anything more than speculative 
value. 


The Seventeenth Century 131 


ROEMER (1644-1710) 


VELOCITY OF LIGHT 


OuAus RoEMER was born at Aarhus in Denmark, was 
educated at the University of Copenhagen, and shortly 
thereafter went to Paris to become the tutor of the eldest 
son of the then King of France (Louis XIV). Here, be- 
ing associated with Picard and Cassini in several discov- 
eries of note, he acquired a high reputation as an astrono- 
mer, in consequence of which he was made a member of 
the Academy of Sciences in 1672. 

The important discovery for which he has the sole credit 
was, that light, which up to that time had been regarded 
as a phenomenon of an instantaneous nature, required an 
appreciable time for its transference through space, and 
that it traveled at a speed of approximately 186,000 miles 
in. a second of time. This conclusion came as the result of 
his investigations on the subject of aberration, a term ex- 
pressing the apparent change in the position of stars dur- 
ing the year, and in connection with the eclipses of the 
satellites of Jupiter. The analogy of a man running through 
a rain storm, when the drops of rain are falling vertically, 
is generally employed to illustrate the phenomenon. To 
the man the drops appear to be falling slantingly, and from 
the direction to which he is moving, so that his face and the 
front of his clothing will receive a larger number of them 
than his back. In a like manner light, coming directly to 
an observer on the earth, will seem to arrive on a slant, 
because the earth is in motion at a velocity of 19 miles 
per second, either towards or away from the source of light, 
while simultaneously the source itself is also in rapid mo- 
tion towards or away from the observer. The net result is 
the apparent movement of the star in the vault of the sky 
through the curve of a minute oval (circle or ellipse). 

The nature of this curve, it dimensions, and the direc- 
tion along which the star travels in it—with or opposite to 
that of the hands of a clock—afford data from which the 
velocity of light may be calculated. 


132 Beacon Lights of Science 


The exact velocity is 186,350 miles per second (299,86U 
kilometers). This figure is the result reached after a large 
number of most careful observations, and appears to be 
invariable. It makes no difference whether the source is 
moving towards or away from us. In this respect the phe- 
nomenon is like that of sound, which travels at the invari- 
able rate of 1100 feet per second through a normal atmos- 
phere. If the source of the sound is approaching, more of 
the undulations in the air than otherwise reach the ear per 
unit of time, and the pitch of the note is higher. If it is 
receding, the contrary effect of a lower note is produced. 
It is the same with light. If we are approaching its source 
faster than it is receding from our position in space, more 
of its undulations per unit of time will arrive to the eye, 
and the effect produced will be that of unusual brightness. 
On the other hand, if the distance between the source and 
the observer is increasing, the opposite effect results. 

There is, however, a marked difference in character be- 
tween sound and light waves. The former are longitudi- 
nal, being impulses which travel forward and back in the 
direction in which the effect is propagated, resulting in vi- 
brations which are alternately those of compression and 
release from compression. But light undulations are of a 
transverse kind, similar to those which pass along a rope 
when one end of it is fixed and the other shaken. 


LEIBNITZ (1646-1716) 


MATHEMATICS AND PHILOSOPHY 


GOTTFRIED WILHELM VON LEIBNITZ was a native of the 
city of Leipsic, Germany, the son of the professor of law 
in the local university. He was well educated in the expec- 
tation that he would follow the profession of his father, 
but at an early age exhibited decided inclinations towards 
literature and the sciences; and not being under the neces- 
sity of earning his living, he enrolled himself at the age 
of eighteen at the University of Jena as a student in the 
higher mathematics. In 1666 he received his degree ot 


The Seventeenth Century 133 


doctor of laws from the university of Altdorf, and in the 
following year entered the personal service of the Elector 
of Mainz, undertaking legal work, while at the same time 
employing his leisure hours in writing and publishing sev- 
eral treatises on theological subjects. In 1672 he undertook 
a political mission to Paris, but not meeting with the suc- 
cess hoped for, he journeyed to London, where he formed 
the acquaintance of Newton and Huygens, both of whom 
were attracted by his evident ability and charm of manner. 
In 1676 he accepted the position of librarian and privy 
councilor to the Duke of Brunswick, and while engaged in 
writing the history of this famous House he assumed the 
direction of the ducal mines in the Harz mountains which, 
for five centuries had been highly productive of copper, 
silver, lead, zine and iron, but had been neglected, and 
were in a deplorable condition. Under his vigorous man- 
agement they became again profitable. 

Later, having moved to Berlin, he organized and was 
elected the first president of the Society of Sciences there, 
which in after years became the National Academy. Sub- 
sequently he was employed to organize similar institutions 
in Dresden, Vienna and St. Petersburg. In recognition of 
his success in the last case, he was given a pension by the 
Czar, and the title of Privy Councilor. In 1714 he wrote 
and published his most noted philosophical work entitled 
‘“Monadologie,’’ in which he set forth the main details of 
his system. This drew him into a controversy with the 
English theologian and metaphysician, Samuel Clark, and 
while it was in progress his death occurred. 

It will be evident from this brief résumé of his life activ- 
ities, that Leibnitz was a man of ability and versatility. In 
his time the sciences—except mathematies—were in their 
infancy, and the aspect they now present, that of classified 
and organized knowledge gained by experience, had not 
been clearly recognized as a distinguishing feature. The 
influence of the Greek philosophers, and of the medieval 
metaphysicians and theologians, was yet paramount in the 
minds of the educated almost everywhere, and controversy 
or discussion was regarded as a more fruitful method of 


134 Beacon Lights of Science 


arriving at correct conclusions, than the study of nature, 
and of the causes underlying its observed phenomena. 
Therefore his fine mental equipment did not lead, during 
his life, to any notable addition to the current stock of 
knowledge, excepting in the department of mathematics, 
and in that branch of it which has become known as the 
Calculus, the invention of which is popularly ascribed to 
Newton. But its fundamental concept was really first defi- 
nitely enunciated by Archimedes (287-212 B.c.), who, in 
his efforts to solve the ancient problem of the squaring of 
the circle, reached an approximately correct value of the 
relation of the diameter to the circumference (7), by as- 
suming the latter to be the mean between the measurements 
of circumscribed and inscribed polygons with a continu- 
ally increasing number of sides up to the limit of numerical 
representation. This was called the ‘‘Method of Exhaus- 
tions.’’ The next step was not taken until Kepler (1571- 
1630) introduced the conception of infinity into geometry, 
by picturing the surface of a circle as composed of an in- 
finite number of triangles, each with its apex at the center, 
and its base on the circumference; and the cone as a collec- 
tion of an infinite number of pyramids. Further steps 
were taken in turn by Cavalieri, Wallis, Descartes and 
Fermat in the development of these ideas, but it was the 
part of Newton and Leibnitz, working separately on the 
conceptions of their predecessors, to invent a system of no- 
tation by the use of which their ideas could be organized 
into a comprehensive and practical method of reaching re- 
sults. That of Leibnitz was published in 1684, while New- 
ton’s, though worked out a dozen years before, and ex- 
hibited privately to friends, did not appear in print until 
1687. The fundamental ideas in the two were substantially 
the same, but the symbols and systems of notation differed. 
In consequence of his great reputation Newton’s system 
was at first universally adopted, and the science went under 
his name of ‘‘Fluxions.’’ On the continent the notation of 
Leibnitz was quickly recognized as the better of the two, 
but in England that of Newton continued to be employed 
for nearly a century before it was superseded by the other. 


The Seventeenth Century 135 


It is generally admitted that to Newton should be given 
the credit of developing the Calculus to a point where, it 
became of practical use in solving problems of a general 
nature; while to the German belongs the honor of having 
devised the better system of symbols to conduct its opera- 
tion. 


HALLEY (1656-1742) 


ASTRONOMY 


THE astronomer, Edmund Halley, was a native of Hag- 
gerston, a suburb of London. He was educated at St. 
Paul’s school in that city, and afterwards at Oxford. In 
1678 he was elected a fellow of the Royal Society, and sent 
on an important mission by that organization to the vicin- 
ity of Dantzic in East Prussia. In 1682, in collaboration 
with the French astronomer, Cassini, at Paris, he observed 
the coming and going of the great comet of that year, which 
now bears his name. In 1699, for the purpose of investi- 
gating the variations of the magnetic compass, he made a 
long sea journey under government auspices, and collected 
such an extensive and valuable mass of data on the sub- 
ject, that he was given the rank of captain in the Navy, 
with half pay for life. Shortly thereafter he made the 
survey of the coast of Dalmatia for the Austrian govern- 
ment. In 1703 he was appointed professor of geometry at 
Oxford, and in 1713 became secretary of the Royal Society. 
In 1721 he was made Royal Astronomer. 

Halley’s contributions to the advance of knowledge in 
his time were many and important, but the one that has 
brought him the greatest honor was his correct prediction 
of the return of the great comet of 1682. To Tycho Brahe 
was due the discovery that these bodies are extraneous to 
our atmosphere. Newton later showed that their move- 
ments are subject to the same laws that control the planets 
in their orbits. Halley, deeply impressed with what he 
had seen while working with Cassini, began to investigate 
the history of recorded observations in the past of these 


136 Beacon Laghts of Science 


bodies, of which fortunately a large number were available. 
By these means he was able to identify the comet of 1682 
with one which appeared in 1607, and another in 1531, 
whose orbital elements, in both cases, agreed with those he 
had recorded when working with Cassini. He then ven- 
tured to predict the return of the wanderer at the end of 
1758 or early in 1759. It arrived and reached perihelion 
on March 12, 1759. Its next appearance was set by astron- 
omers for a date between the 4th and the 13th of November, 
1835. It passed the sun on the 16th of that month. And 
again, in the early summer of 1911 it arrived almost ex- 
actly on the hour prescribed. Its period is about 76 years. 
It is now known to be identical with the comets which ap- 
peared in 1456 and 1378, the last having been recorded by 
Chinese observers, and it is believed to be the same as those 
mentioned historically as of the years 1145, 1066, 986, and 
12’ B.c. 

Halley was the first to suggest the observation of the 
transit of Venus across the face of the sun as a means of 
determining the sun’s diameter. 


BRADLEY (1693-1762) 


ASTRONOMY 


JAMES BRADLEY was reared at Sherborn, England, was 
educated at Oxford, and in 1721 was appointed to the 
Savilian chair of astronomy there. In 1726 he announced 
the method—original with him—of obtaining longitudes by 
means of the eclipses of the satellites of Jupiter, and in 
1729 his explanation of the phenomenon known as the — 
Aberration of Light. These two notable contributions to 
the advance of knowledge won him the appointment in 
1742, after the death of Halley, of the post of Royal As- 
tronomer, a position which he filled with great credit to 
himself and the State during the remainder of his active 
career, accumulating a mass of accurate observations which 
have proved to be a perfect mine of data of the very high- 
est value to the science of astronomy. 


The Seventeenth Century 137 


As light from the heavenly bodies requires an appreci- 
able time to travel through space; as those luminous bodies 
are in motion; and finally as the earth, from which we view 
them, is itself continually traveling in its orbit around the 
sun and revolving on its axis, there is in progress at all 
times an apparent displacement of the fixed stars in the 
vault of the sky, from what would be their true position 
with respect to us, if all motion in the Universe ceased, and 
the transmission of light was an instantaneous phenomenon. 
It was Bradley who accounted mathematically for this per- 
petual slight displacement, which was revealed to observa- 
tional astronomers whenever the position of any of them 
was accurately taken and compared with positions previ- 
ously noted. Each appeared to move in a minute oval, 
which, in effect, was mainly a reproduction in minimum 
of the vast oval of the earth’s annual path around the sun. 

Yet even Bradley’s first explanation was not wholly sat- 
isfactory, for the figure which he deduced as the ‘‘ constant 
ot aberration’’ did not account for all the facts observed. 
For nearly 20 years he studied the problem, and finally, in 
1748, announced that all the elements of the phenomenon 
could be satisfactorily and perfectly explained, by assum- 
ing an oscillatory motion of the earth’s axis, completed 
during a revolution of the moon’s nodes, that is, in a period 
of about eighteen and a half years. He gave to this factor 
of the problem the name of the ‘‘nutation of the earth’s 
axis.’”? For this discovery he was awarded the Copley 
medal. 

The value of the constant of aberration is 30.47 seconds. 
It represents the linear amount by which the position of 
a star will vary throughout the year from its average posi- 
tion. It is a very important figure in astronomical work. 
For, combined with the known velocity of light, it gives 
the earth’s orbital velocity in miles per second, and from 
that, by a simple calculation, the semi-diameter of the orbit, 
which is the mean distance of the earth from the sun. This 
last is one of the fundamental astronomical units or yard 
sticks, and its exact evaluation is regarded as among the 
most important of astronomical problems. 


138 Beacon Laghts of Science 


MACLAURIN (1698-1746) 


MATHEMATICS 


CoLIN MACLAURIN was a native of Kilmodan in Scot- 
land, and was educated at the University of Glasgow. He 
exhibited unusual mathematical ability in early youth, and 
in 1717 became professor of that science in the University 
of Aberdeen. Two years later, through the kindly interest 
of Sir Isaac Newton, he was elected a member of the Royal 
Society. In 1726, having meantime traveled on the con- 
tinent, he was appointed to the chair of mathematics at 
the University of Edinburgh, where he remained until that 
city was captured by the ‘‘Young Pretender’’ (Prince 
Charlie), who later met with decisive defeat at Culloden. 

His principal contribution to the progress of science 
consisted in his development of the fluxional calculus, 
which gave him a standing at the time as a mathematician 
second only to that of Newton. Another important discoy- 
ery, or rather deduction from his studies in the field of 
mathematical physics, was his demonstration of the fact 
that arevolving homogenous fluid or plastic substance would 
assume the shape of an ellipsoid, which threw a new light 
on the phenomena of the tides, as well as on the subject of 
the correct figure of the earth. 

The Calculus is: that branch of the science of mathe- 
matics which deals with quantities whose properties (di- 
mensions, masses, volumes, positions, rates of motion, etc.) 
are constantly increasing or diminishing. Inasmuch as 
nature in practically all its phases is continually in a state 
of flux (growth or decay, enlargement or decrease of mass, 
approach or recedence, ete.) it is not difficult to understand 
the slow progress made by science before the Calculus came 
into existence as a mathematical tool. 

For a simple illustration, take the case of the ball thrown 
by the pitcher towards the batter in the national game of 
baseball. It leaves the hand of the former at a certain 
initial velocity which may be ascertained, and reaches the 
place of the latter within a period of time which can also 


The Seventeenth Century 139 


be determined. The distance between the two is known. 
From these elements it is a simple matter to figure the 
average speed of the missile during its flight. But, if it is 
desired to know either its position or its velocity at one 
or more places of the transit, the problem becomes more 
complicated. For, at the instant the ball leaves the hand 
of the thrower, not only does its velocity begin to vary, 
but also its height above the horizontal plane of the field 
upon which the game is played, besides being more or less 
affected by windage; and these changes continue to occur 
incessantly throughout its journey. Of course, a small 
problem might be approximately solved at several points 
experimentally, by taking photographs and time data along 
the route between the two stations. But if the movement 
of a bullet from a high power rifle, or of a shell from a 
cannon were under consideration, experimental solution 
would be practically impossible with any degree of accu- 
racy. 

When finally the problem is transferred into space, and 
becomes one related to the motions of the heavenly bodies, 
the true field of the Calculus is reached. It is the science 
of the infinite at both its extremities of minuteness and 
enormity; of variations of dimension so small as to be un- 
imaginable by the mind, yet which exist as truly as does 
the sum of them, which become at length apparent to the 
senses as definite portions of space and time. 

It is of course impossible at any reasonable length to 
explain even the fundamental principles of the Calculus, 
much less any concrete operations of them. Maclaurin was 
by no means the first to enter its domain. In the old prob- 
lem of the squaring of the circle Archimedes made a not- 
able beginning when he pictured the latter as a polygon 
with an innumerable number of sides. Kepler (1571-1730) 
took a further step by assuming the area it enclosed to be 
composed of an infinite number of triangles, with their 
vertices at the center and their bases on the circumference. 
Following him, Cavalieri (1598-1647), Descartes (1596- 
1650), Fermat (1601-1665), Leibnitz (1646-1716) and 
Newton (1642-1727) each took a hand in its development. 


140 Beacon Lights of Science 


By the last the science was given the name of the ‘‘ Flux- 
ions,’’ its basal idea to him being that of infinitesimal vari- 
ations in velocity. Many other notable -mathematicians 
have since contributed to its progress. As it stands today, 
still capable of growth, its power as a method of reaching 
out into infinity, and of obtaining reliable solutions from 
premises that can only be imagined, is one of the most 
remarkable proofs of the capacity of the human mind. 


DE JUSSIEU (1699-1776) 


BOTANY 


BERNARD DE JUSSIEU was a native of Lyons, France, and 
graduated in 1720 at the University of Montpelier with the 
degree of M.D. From there he went to Paris, and becoming 
deeply interested in botanical research studied that science 
exhaustively at the Paris University. In 1722 he was ap- 
pointed demonstrator at the Jardin du Roi (des Plantes). 
His devotion to botany—which at first was mainly due to 
a desire to learn the medicinal properties of herbs, was 
quickly merged into research for the purpose of acquiring 
a better understanding of the relation of planis to each 
other, and ended in a systematic classification of the mem- 
bers of the vegetable kingdom. He succeeded during his 
life in correctly laying a scientific foundation for his sys- 
tem. After his death this was elaborated and carried for- 
ward to completion by his nephew, Antoine Lamont. The 
latter, after thirty years of study, gave to the world his 
‘Genera Plantarum,’’ in which the classification now reec- 
ognized was outlined, and detailed as far as members of 
the vegetable world then known would permit. To Bernard 
therefore is due the high honor of placing botany among 
the sciences, and to his nephew that of giving it to the world 
in detailed form. 

The Greeks were probably the first who attempted bo- 
tannical research. Aristotle and Theophrastus classified 
the vegetable world under the heads of trees, shrubs and 
herbs. As they had no basis of technical knowledge on 


OFT 260d bmrv7 samuaiag fo KwapprIp jpuo1jvN O) 








\ 


ry s 
A a 
* .e 
gan oe 
s La’ = a Sata i 
‘ A a eS ak 
“ aco 
. 7 Ca 
rr; a 
. > 
» a 
- me 4 Boa Me 
a rei 
i = : 
~ “” 
é 
7 _ 
A * L 7 
if : * 
7 4 
* 
, 
} 
~ x 
- i i 
' * 7 
J 





THE LiGhARY 
OF THe 


UNIVER ry ar LOS 


= Laat 
m 
° ° ‘TA 
La iG @ 
bat  ” 
= 
v 
= cad 
3 
" eo = 
‘ss? o 
r : : 
i a f - 7 
* A oiee 2 
\ ~* . 
c _ 
\ 
¥ = 
> 
" r ‘ 
nd al U 
> at bo? 
a bo Sa 
ey a es >) wo 
oo, «eee 2 450°" © 
1 
-— 
<n é 
ay 
i + ‘ = § 


The Seventeenth Century 141 


the subject they could go no further. From their time 
until that of Linnaeus (1707-1778) the herbalists, who re- 
garded plants chiefly if not wholly from the point of view 
of their possible medicinal virtues, were the only class of 
students who could be ealled botanists. 

The Linnean classification, like that which he devised for 
animals, was based entirely on observation of external 
peculiarities. He grouped the vegetable world under 
twenty-four heads, depending upon the number, relative 
position and other visible qualities of the male and female 
organs, whenever these could be detected. This was of 
course an advance—and in the right direction—on the ran- 
dom work of the herbalists, and for nearly a century was 
regarded as satisfactory. 

Under the system elaborated by De Jussieu and his 
nephew, and subsequently expanded by de Candolle (1818- 
1821), Endlicher (1836-1840), Brogniart (1848), Lindley 
(1846), Braun (1864), Hichler (1883) and Engler (1892), 
the kingdom of the plants is divided into four great groups, 
as follows: Thallophytes, such as sea weeds and fungi; 
Bryophytes, as mosses and liverworts; Pteridophytes, as 
ferns, ete.; and Spermatophytes, including all others. The 
last is sub-divided into Anigosperms, which includes all 
whose seeds are inclosed in a protecting vessel, as peas and 
apples; and Gymnosperms, whose seeds are not so pro- 
tected. All of the latter are either trees or shrubs, and are 
mostly of the evergreen kind, and resinous in character. 
Of course, all of these six major groups are again and 
again sub-divided and, as knowledge of the vegetable world 
orows, will doubtless undergo further classification. But 
it is not thought that the foundations laid with so much 
patient study by De Jussieu and Lamont will ever require 
serious amendment, 


Se Ae 


ries 
af ’ + 


; " i! 
rf as od 
y rey eat 


ies yt NOP. | x 
Allse 7 Oe! 
, i Pist vi ~* 


Pea 

Lot 
Pa 
wists 
"i 


ta 


Ph 
Be VES 


af 
(5 pak tt ‘, 
i Saint 
io aA Alita pany 


ary 


1 


ae uD: 
‘ 4 ¥, 

a | A i Mabe 
ASM hing 
rio Tet a’ 





V 
THE EIGHTEENTH CENTURY 


During this period science made remarkable progress in the matter 
of establishing fundamental principles. And, simultaneously certain 
racial movements occurred among the people of Europe that were 
to culminate in the following century in the rise to importance of 
that political doctrine called the ‘‘Balance of Power.’’ As this 
exercised a marked effect on the development of the sciences it will 
be both interesting and instructive to note briefly the steps in the 
process. 

Great Britain, under the reigns of William and Mary, Anne, 
George I, IJ and III (1689-1820), became strong and wealthy, but 
in the final quarter of the period lost its American colonies (1775- 
1783). France first rose to power under Louis XIV, XV and 
XVI, but its upper classes became idle and profligate. The Revolu- 
tion, which began in 1789 and lasted until 1792, brought Napoleon 
to the surface. Under his leadership France became the predominant 
power of Europe. Austria, through the period, steadily lost ground 
in western Hurope, but gained enough in the east to hold its position 
as a nationality of importance. In 1713 the first Hohenzollern 
(Frederick I) was crowned king of Prussia. He was followed in 
turn by Frederick the Great and Frederick William. Under these 
three, Prussia became the dominant element among the Germanic 
people. Italy during the century continued a divided nationality 
under the rule of France, Austria, and the Pope. Towards the end 
of the period the territories of the Papal States were considerably 
reduced. 

Of some 63 scientists of note listed in this period, 23 were French, 
16 British, 12 German, 4 American, 3 Swedish, 3 Italian, and 2 
Russian. 


GRAY ( ?-1736) 


CHEMISTRY 


STEPHEN GRAY was a man of whose ancestry and birth 
practically nothing is known. He was in fact a Charter- 
house pensioner in youth, which means that he was the son 
of paupers. However, he managed to acquire the rudiments 
of an education. With this meager equipment, and while 
earning his living by manual labor, he discovered certain 
basic facts in electrical phenomena. To him we owe the 
division of substances into the two grand classes of con- 
ductors and non-conductors, or, as he first termed them, 
into ‘‘electrics’’ and ‘‘non-electrics’’; and the proof that 
many of the latter class could, by simple contact, be con- 
verted into the former. He demonstrated clearly the prin- 
ciple of insulation, and showed that it was an inherent 
quality resulting from the nature of the materials of which 
they were composed. Naturally, on account of his educa- 
tional limitations, and the youth of the science in his time, 
several of the theories he advanced to account for some 
of the electrical effects he observed, have since been aban- 
doned. 

Now that the chemical atom has been decomposed into 
electrons and protons, and matter, as heretofore under- 
stood, has proved to be nothing more than a special mani- 
festation of energy, the division of substances into electrics 
and non-electries, or into conductors and non-conductors, 
does not possess the significance it did in the days of Gray. 
Nevertheless, it is still necessary to ascertain if possible 
why the electrical current will pass with ease along or 
through certain substances, and with difficulty or appar- 
ently not at all in the case of others. For upon the prop- 
erty called insulation depends the ability to compel the 


145 


146 Beacon Lights of Science 


current to go where it is desired, and to keep away from 
places where its presence would be highly objectionable. 

Broadly speaking, if the urge of the current is strong 
enough, it will pass along or through any known insulator. 
The fact that it exhibits disinclination to journey through 
certain substances, or, to put it the other way, that certain 
materials object most strenuously to its passage, is held by 
physicists to indicate a molecular state of affairs in non- 
conductors very different from that which exists in con- 
ductors. The metals as a class give easy passage to the 
current, silver possessing the capacity to the highest de- 
gree. Yet tungsten and several others exhibit the prop- 
erty to so limited an extent that they are used in the 
manufacture of resistance coils through which the current 
experiences such difficulty in passing that it becomes light 
and heat during the transit, returning instantly to the 
condition of electricity as soon as the detaining bridge is 
crossed. 

On the other hand glass, porcelain, dry air, chemically 
pure water, and almost all the hydrocarbons like silk, 
paraffin, rubber, ete., are typical representatives of the 
non-conducting or insulating class. Yet moist air, impure 
water and hydrocarbons moderately adulterated with min- 
erals will give easy transit to a strong current. Again, an 
increase of temperature above the normal decreases the 
conductivity of all the metals, but has the opposite effect 
upon the insulating substances. Glass loses the property 
almost completely at red heat, while copper under the 
same treatment becomes a very indifferent conductor. 


BERNOUILLI (1700-1782) 


MATHEMATICS 


DANIEL BERNOUILLI was a native of Groningen, Ger- 
many, and was educated at home under private teachers. 
He belonged to a family noted for mathematical ability in 
several generations. Following his natural inclinations he 
specialized in that science and in medicine, and attained 


The Exghteenth Century. 147 


a high rank as an instructor and investigator in anatomy, 
physics and botany. He was successively a professor in 
one or more of those sciences in the Universities of St. 
Petersburg, Groningen and Basle, became a member of 
most of the important European Academies of Science and 
a writer of note on his subjects. His principal literary 
production, entitled ‘‘Hydronamica,’’ was published in 
1745. In it he developed for the first time the kinetic 
theory of gases, which is regarded as his great contribution 
to the advance of knowledge. 

As the comparatively modern science of organic chem- 
istry is practically based upon a correct knowledge of the 
properties of gases, it will be clear how important was the 
foundation laid by Bernouilli. Unless the vacuum be re- 
garded as material, the gaseous is the simplest form of 
matter. In it the molecules are most widely separated, and 
consequently their influence upon each other must be at 
a minimum. This means that the number of causes deter- 
mining the properties of a gas must be fewer and much 
less complex than those in a liquid or solid, where the 
forces of mutual attraction are more powerful. Boyle, 
Dalton, Gay-Lussac, Avogadro and others discovered the 
laws which express the action of gases as a class when by 
themselves. It was the part of Bernouilli to first give ex- 
pression in mathematical language to the principles under- 
lying these; that is, the principles that govern the molecule 
of matter in its motions—as in gases and liquids—and 
which produce such phenomena as diffusion, osmosis, evapo- 
ration, dissociation, energy conduction, fluid pressure, vis- 
eosity, etc. From his analysis of the forces in action among 
them it has become possible to calculate the approximate 
number of molecules in any given volume at atmospherie 
pressure, their mean distance apart, the mean free path 
of each and the actual proportion of space occupied by 
them, which was found to be about one-four-thousandths 
part of the volume in which they were supposed to be con- 
fined. From this, of course, the actual molecular volume 
itself could be readily deduced. 


148 Beacon Lights of Science 


FRANKLIN (1706-1790) 


ELECTRICITY 


BENJAMIN FRANKLIN, born in Boston, was the fifteenth 
of a family of seventeen children. His father was an 
English emigrant, and conducted a manufactory where 
tallow candles were produced. His mother—a second wife, 
was also of British birth. Both parents were deeply re- 
ligious, and as Benjamin was the tenth son he was dedi- 
eated from infancy to the ministry. But as he grew up, 
his active mind and inquiring disposition led him in a dif- 
ferent direction. Leaving school at an early age, he worked 
for a year in his father’s factory, and then apprenticed 
himself to an elder brother, who was a printer, and the 
founder of the New England Courant, one of the earliest 
American periodicals. After a while, finding the associa- 
tion irksome, he broke his indentures, and left by ship for 
New York. Finding no work there he went on to Philadel- 
phia and arrived almost penniless. But he quickly found 
employment and made friends, and rapidly became an ac- 
tive force in the community. In 1725, under the advice 
of the governor of the colony, he went to England to pur- 
chase equipment for a newspaper venture he contemplated, 
but meeting with financial disappointments he was com- 
pelled to go to work at his trade in London. In the follow- 
ing year he was able to return to America, and in 1729, 
he obtained control of the Pennsylvania Gazette, and 
speedily made it a great success. In the following year he 
married, and during the next quarter of a century became 
known as the foremost literary character of the American 
colonies. 

It was in this period of his life that science, and par- 
ticularly that budding department of it clustering around 
the phenomena of electricity, attracted his attention. The 
well-known experiment with the kite, in which he proved 
the identity of lightning with the electrical current, took 
place in 1752, when he was at the age of 46. This brought 


The Eighteenth Century 149 


him immediate recognition in every part of the educated 
world. It is properly regarded not only as one of the great 
discoveries of science, but as a most ingenious and effective 
method of establishing a theory evolved entirely from 
study. In recognition of its importance, he was given the 
degree of LL.D. by the Oxford, Edinburgh and St. Andrews 
universities, was made a fellow of the Royal Society of 
London, and awarded the Copley gold medal. The last 
consisted of the interest on a fund of £100, established by 
Sir Godfrey Copley for the encouragement of students in 
‘“natural knowledge.’’ The first award was made in 1731, 
the second in 1734, and in 1736 the bequest was converted 
into a gold medal, to be awarded annually under the super- 
vision of the Royal Society. 

Besides this notable achievement, and the invention of 
the excellent Franklin stove, which is as much a favorite 
now as it was at first, wherever stoves have to be used, the 
remainder of his memorable life was devoted more to states- 
manship than science. When the Revolutionary war was 
threatened, he made every honorable effort to avert it; 
but when it appeared inevitable, he took his stand firmly 
with the colonies, became a member of the Continental Con- 
gress, signed the Declaration of Independence, and was ap- 
pointed the political representative of the new nation in 
Europe, where his reputation, his dignity of character, 
charm of manner and wisdom, enabled him to secure for 
his country the material and financial aid, which ultimately 
made it possible for Washington to bring the war to a 
successful end. 

In 1785 he returned to America, and immediately as- 
sumed a prominent part in the establishment of the young 
republic. Though at the time nearly 80 years old, he be- 
came a member of the Executive Council of the nation, the 
Governor of the colony of Pennsylvania, and a member of 
the convention called to form the national constitution. 
In all these fields of activity he displayed extraordinary 
vigor and vision. One of his last acts was to sign a memor- 
ial by the Pennsylvania Society for the abolition of slav- 
ery. Upon his death at the ripe age of 84, his remains 


150 Beacon Laghts of Science 


found a resting place in the graveyard of Christ’s Church, 
in Philadelphia. 

In stature, Franklin *was a little under six feet, solidly 
built, with a fair complexion, and steady gray eyes. His 
manner was extremely affable and winning. Though un- 
connected with any religious organization, he displayed 
throughout his life all the characteristics of an honest, 
conscientious, and simple-minded gentleman. 


BUFFON (1707-1788) 


NATURAL HISTORY 


GEORGES Louis LEcLERC, Comte de Buffon, of wealthy 
and titled ancestry, was born at Montbard in central 
France. He was liberally educated both at schools and by 
travel, and became an eminent writer, especially on the sub- 
ject of animals and animal life. His principal work en- 
titled ‘‘ Natural History’’ in 44 quarto volumes (a part com- 
pleted after his death) was published in the years between 
1749 and 1804, and for nearly a half century thereafter 
ranked as a classic, mainly because it was the first of its 
kind in which all the current knowledge of the day on the 
subject was collected and related in an interesting and 
non-technical way; in addition to which it was profusely 
illustrated with really good pictures. 

Buffon was in no sense a Scientist, not being by inelina- 
tion or training either an observer or an investigator of 
natural phenomena. Inheriting both wealth and social po- 
sition, and possessing an attractive personality, he devoted 
the whole of his maturity to studies in mathematies, litera- 
ture and physics, and thus acquired a standing among stu- 
dents and investigators which secured his election in 1739 
to the Academy of Sciences, and in 1763 to the French 
Academy; and through his social position the appointment 
of Keeper of the Royal Museum—which subsequently be- 
came the Museum of Natural History—and the Jardin des 
Plantes. In this pleasant environment where he passed his 


The Eighteenth Century 15) 


winters, he made those natural history notes which, during 
the summer, he worked up so delightfully at his ancestral 
home at Montbard. 

In the character of a collector and compiler of informa- 
tion gathered by others, he performed a notable service for 
the increase of knowledge in his day among the masses to 
whom, for many years after his death, his volumes were 
standard publications on their subject. Even among scien- 
tists they met with favor for, making no pretense of being 
one himself, he gave expression in them to many thoughts 
which later bore interesting and valuable fruit. For in- 
stanee, he called attention to the fact of the presence and 
absence of certain varieties of animal life in certain parts 
of the world, as elephants in Hindustan, the East Indian 
Isles and Africa coupled with their total absence else- 
where; the confinement of the lion to Africa; the wide dis- 
tribution of the deer family, excepting Africa, where only 
two varieties have been found, and they only in the north- 
ern part, while the antelope is particularly abundant 
throughout the whole continent; and other similar pecul- 
larities; and intimated that when the subject was thor- 
oughly worked up it should lead to reliable conclusions as 
to the past history of the different and disconnected parts 
of the land surfaces; a view that has been amply verified 
since. 

On the other hand, he did not hesitate to speculate most 
fantastically in the domain cf geology, and on the causes 
of the distribution of human varieties. But it is to be re- 
membered that then the age of the world, and of all the 
living beings upon it, was regarded as a matter definitely 
settled by the creation account in the book of Genesis, and 
its details by the computations of Bishop Usher. Also that 
he lived at a time when it was still unwise, if not unsafe, 
to express publicly opinions that to any appreciable extent 
ran counter to the orthodoxy of the day. In spite of this, 
however, there may be found in his volumes remarks which, 
if not intended ironically, may be construed into a belief in 
the mutability of species, and of their derivation by descent 
and variation from earlier forms, and thus to be to some ex- 


152 Beacon Lights of Science 


tent anticipatory of the theories later advanced by Lamarck 
and Darwin. 

It is generally thought, however, that the chief end 
sought by Buffon in his ‘‘ History’’ was entertainment for 
the reader, and if so, he succeeded admirably, for it was 
the most widely read of all the pseudo-scientific literary 
products of the time, and for nearly a half century after- 
wards. It is a curiously interesting fact that Cuvier 
(1769-1832), the father of comparative anatomy, while 
ealling attention to its many errors, commended it as a 
whole, because it clearly called attention in many places 
to the fact that the ‘‘history of life on the globe was really 
the account of a series of advancing changes’’; and yet, 
when Lamarck drew his specific conclusions from this ad- 
mission, Cuvier would not accept the implication, because 
of the strong influence of his early religious education on 
his mind. 


LINNAEUS (1707-1778) 


NATURAL HISTORY 


CARL VON LINNE, better known by his Latinized name of 
Carolus Linnaeus, was born at Rashult in Sweden, and was 
destined by his parents—as their first born—for the min- 
istry. But at a very early age he exhibited so decided a 
preference for the study of Nature in its aspect of plant 
life, that he was encouraged by friends to persist in his 
desires. One of these, a physician by the name of Roth- 
mann, aided the boy materially with books on physiology, 
botany and medicine, and finally induced his father to 
allow the son to follow his own inclinations. These led 
him to place himself first under the instruction of a noted 
herbalist at Lund in 1727, after which he entered the 
University of Upsala, where the scientist Rudbeck occupied 
the chair of botany, physics and mathematics. Being en- 
tirely without means, and declining even the small allow- 
ance which his father’s very limited means enabled him 
to offer, he soon found work as assistant to the historian, 


The Exghteenth Century 153 


Celsius, and later to Rudbeck himself, who appointed him 
director of the garden of the institution. 

In 1782, carrying his entire outfit on his back, and pro- 
vided by the Academy of Sciences of Upsala with only the 
equivalent of $120 in Swedish money, he made a collecting 
trip of over 5000 miles in Lapland, and returned with ma- 
terial which enabled him to write and publish his first 
book—‘‘Flora Lapponica.’’ Following this, at the invita- 
tion of its governor, he made a second eollecting tour 
through the province of Dalecarlia in central Sweden, giv- 
ing lectures on botany and zoology whenever he could col- 
lect an audience. It was on this trip that he met, at Fah- 
lun, the estimable lady who afterwards became his wife. 
Through the influence of her father he enrolled himself 
at the University at Harderwijk in Holland, where he 
gained his degree in medicine in 1735. In the same year 
he published his first notdble work under the title of 
*<Systema Naturae,’’ which was received with so much favor 
that it ran through twelve editions before the demand for 
it was satisfied. 

This work—the first of its kind to be written—attracted 
the attention of an Amsterdam banker, who was an ardent 
amateur botanist, and led to an association of the two 
under which Linnaeus, while supervising the rearrange- 
ment of the extensive garden, wrote and published in the 
years between 1735 and 1739 six more botanical mono- 
oraphs. These added so greatly to his reputation and 
finances as to enable him to travel in France and England, 
and study the plant life of those countries. In 1739 he 
returned to Sweden, married, and settled in Stockholm as 
a physician. In 1741 he was appointed to the chair of 
medicine at the University of Upsala, and in the following 
year to that of botany. 

His reputation as a naturalist of a high order being now 
fully established, not only in consequence of the papers 
which, from time to time, he continued to publish, but 
also by his great charm as a teacher and lecturer, he began 
to reap the rewards of his previous years of hard work and 
comparative poverty. Students from all parts of Europe 


154 Beacon Lights of Science 


crowded to his lecture room, and many of these becoming 
enthusiastic naturalists, undertook journeys of research to 
remote regions, and sent their collections to their beloved 
instructor, enabling him to write and publish paper after 
paper on his specialty. These were translated at once into 
all the principal languages of Europe, giving him a world- 
wide reputation as the first naturalist of the day. In 1761 
he was elevated to the nobility, and though in 1767 his 
memory began to fail, he remained a highly honored mem- 
ber of the Faculty of the Upsala University until his death. 

The place of Linnaeus in history is that of the man who 
first introduced system in the classification of plant and 
animal life. And though his system was admittedly an 
artificial one for both, and was later displaced by those of 
Cuvier and others, the order which he inaugurated in a 
subject where before had been the greatest confusion and 
empiricism, was a long step in advance in the work of 
accumulating correct knowledge of organic life. His 
adoption of what is known as the binomial system of nomen- 
elature, by which to each organism studied was given a 
specific and a generic name, the first conferring indexiecal, 
and the second mdividual value, coupled with the use of 
Latin roots and words for names, has been followed since 
everywhere, and has resulted in internationalizing the sci- 
ences where, previously, the bar of language had resulted 
in much unnecessary duplication of effort. 


EULER (1707-1783) 


MATHEMATICS 


LEONHARD EULER was born at Basel, Switzerland, and 
is regarded as one of the greatest of the mathematicians. 
He was educated in the university of the city of his nativ- 
ity, and was so precocious as to win his degree of M.A. at 
the unusually early age of sixteen. After graduation he 
specialized in his favorite studies with private instructors, 
devoting also several years to theology, medicine, the 
Oriental languages and such science as the accumulated 
knowledge of the day provided. 


The Eighteenth Century 155 


At the age of twenty-eight, as the result of a severe ill- 
ness, he lost the sight of one of his eyes, and about thirty 
years later became totally blind. In spite of this severe 
handicap he was, throughout his life, a persistent, un- 
daunted and weariless investigator and teacher. At the 
age of twenty, and at the invitation of the Empress of 
Russia (Catherine I), he went to St. Petersburg, and be- 
came an associate of the Academy of Sciences there, serv- 
ing first as a teacher of physics, then of mathematics, and 
finally inspector of the geographical department. In 1734 
he was called to Berlin by Frederick II, and undertook 
the directorship of the department of mathematics in the 
Imperial University. In 1766 he returned to St. Peters- 
burg, and remained there until his death, an honored mem- 
ber of the faculty of the university of that city. 

EKuler’s writings on mathematical subjects were remark- 
ably numerous, including 473 published during his life- 
time, 200 shortly after his death, and 61 more since, at 
different times as they came to light. These are regarded 
as of the highest value, for he possessed a style of unusual 
clearness and easy intelligibility. Partial and even com- 
plete blindness did not lessen his mental vigor. When the 
latter misfortune overtook him, he employed as an amanu- 
ensis a young German who was, by trade, a tailor, and 
whose mathematical education had never progressed be- 
yond the fundamentals. To him he dictated his remarkable 
‘*Introduction to Algebra,’’ in terms so clear and simple 
that his assistant, as the work advanced, became an expert 
algebraist. 

Euler carried his great mathematical faculties into the 
domain of physics. He was the first to deduce the equation 
of the curve of vibration in the phenomena of light rays, 
and to demonstrate their relation to, and dependence on the 
properties of density and elasticity in the medium that 
earried them—the ether of space. As a corollary from 
this, he showed mathematically that in the phenomenon of 
refraction it was the rays of greater length—those towards 
the red end of the spectrum—that underwent the smallest 
rate of dispersion in passing through the prism. In the 


156 Beacon LIaghts of Scrence 


face of the statement by the great Newton that a correc- 
tion of chromatic aberration was unattainable, he investi- 
gated the subject so deeply and thoroughly, that he was able 
at the end to write a prescription under which Dollond, 
the distinguished English optician and instrument maker 
was able to construct a combination of lenses of different 
qualities of glass, which were practically achromatic. 

In versatility of keen mental powers Euler ranks with 
Leonardo Da Vinci. Of all the great mathematicians that 
have arisen to date in the records of the science, he was 
preéminent in the faculty and habit of using that wonder- 
ful tool in solving practical problems in the arts. For 
example, he developed a method of determining longitude 
at sea, which brought him a share of the £20,000 prize 
offered by the British Parliament, the balance going to the 
instrument maker, Harrison, who constructed a chronome- 
ter sufficiently accurate to be used for the same purpose, 
the one checking the results indicated by the other. 


CLAIRAULT (1713-1765) 


PHYSICS 


ALEXIS CLAUDE CLAIRAULT was a native of the city of 
Paris. At an early age he exhibited unusual mathematical 
ability, and was afforded every opportunity to extend his 
education in that line, with the result that at the age of 
eighteen he was elected a member of the French Academy 
of Sciences. In 1736, as assistant to the astronomer, 
Maupertuis, he went to Iceland to measure a degree of the 
meridian. When its length was determined, the flattening 
of the globe towards the pole was demonstrated, which was 
contrary to the opinion that had been expressed by Cassini, 
but entirely in accord with the prediction made by Newton. 

Clairault’s chief accomplishments were his exposition of 
the nature and properties of curves of the third degree; 
and his explanation of the phenomenon of eapillarity. He 
also was the first to complete such an accurate determina- 
tion of the figure of the earth that practically no change 
has since been made in the result he arrived at. 


The Eighteenth Century 157 


Capillarity is a familiar phenomenon, and one that plays 
an important part in vegetable life and soil conditions, but 
is at the same time not easy to explain. At its foundation 
is the property that all liquids possess (in degree varying 
with their nature) of forming a skin of great tenuity and 
considerable tenacity on their surfaces, which always has 
a stronger tendency to contract than to expand, but which, 
when compelled to expand—as in the case of a soap bubble 
—does so at first by drawing some of the liquid from the 
under side of its skin to the outer side, that is, the skin be- 
comes thinner. When all of it has come to the outer side 
of the bubble then, to some extent, but very slightly, 
stretching may ensue between the molecules. When the 
internal pressure exceeds their mutual attraction, the bub- 
ble bursts. This skin-forming property is called ‘‘surface 
tension.’’ When a tumbler of water is carefully filled to 
its brim, it is possible, by delicate manipulation, to lay a 
perfectly dry steel needle on its surface, which will not sink 
until, as the result of a jar, the skin parts under its weight. 

When a glass tube (open at both ends) is completely 
wetted inside and outside, a film of water remains on its 
surface. If now it is dipped vertically into a vessel of 
water, the latter will be seen to rise higher in the tube 
than its level in the vessel, and its shape will be concave, 
that is, lower in the middle than on the sides. This occurs 
because, when the film of water on the inside of the tube 
unites with the skin on the surface, the latter contracts as 
forcibly as it can, and draws the liquid up in the tube to a 
degree dependent on its character and also on the diameter 
of the tube. The smaller this diameter, and the greater the 
mobility of the liquid, the higher it will be drawn, until 
the action of the force of gravitation balances the strength 
of the surface tension, and stops the movement. 

If now mercury be substituted for water, a directly oppo- 
site effect will follow. In the first place the tube, even if 
left for some time in the liquid metal, will retain none of 
it on the outside or the inside of its bore as a film, for clean 
mercury will not ‘‘wet’’ clean glass, as water will. When 
now the tube is dipped vertically into the vessel, the sur- 


158 Beacon Lights of Science 


face of the liquid metal in it will be lower than the surface 
outside, and convex in shape, that is, higher in the middle 
than at the sides. This is because the surface tension being 
stronger than in the case of water, and there being no sur- 
face film in the tube with which to attach itself, the urge 
to contraction draws it down to the main mass of the metal. 

To demonstrate the contractile tendency of a liquid film, 
let a soap bubble be blown on the bowl of a clay pipe. 
When it seems to be at its largest possible size, let the aper- 
ture at the mouthpiece be closed with the tongue, so that 
no air can escape. At once the bubble will begin to de- 
crease in size, and will compress the air it contains to 
an extent that will be quite appreciable when the tongue is 
removed so that it can escape confinement. 

As the temperature of a liquid rises above normal, its 
surface tension lessens until, at the boiling point, the skin 
is ruptured by the bubbles rising through it to escape in 
the form of vapor. Cold water will therefore rise higher 
in a tube than when warm. 


D’ALEMBERT (1717-1783) 


MATHEMATICS 


THE real name of this brilliant Frenchman was Jean le 
Rond. He was abandoned by his parents as an infant on 
the steps of the chapel dedicated to that saint, but was 
kindly cared for by the motherly wife of a workingman, his 
father contributing secretly to his support, and later pay- 
ing liberally for his education at one of the Jansenist col- 
leges where, at an early age, he displayed unusual ability 
in mathematics and in the sciences. The name by which he 
later became known was an assumed one, the reason for its 
adoption never having been given by him. At the age of 
twenty-two he published a notable monograph on the in- 
tegral calculus, and a couple of years later another on the 
refraction of light: In 1743 his treatise on dynamics ap- 
peared, which marked an epoch in the history of physics; 
for in it he gave expression to one of the fundamental 


The Eighteenth Century 159 


principles of that science, to the effect that ‘‘impressed 
forces are equivalent to the effective foree.’’ Such a state- 
ment today would seem self-evident, but in the middle of 
the 18th century it was not only new, but the first one to 
epitomize what became later to be known as the theory of 
the conservation of energy. Another monograph published 
in 1744 contained the first conception of the calculus of 
partial differences, and a third which appeared four years 
later, contained the earliest analytical solution of the phe- 
nomenon of the precession of the equinoxes. In 1751, in 
association with Diderot, one of the most brilliant and 
versatile writers of the time, he undertook the editing of 
the great French encyclopedia, and contributed many arti- 
cles on science and philosophy to its pages. 

The name by which he was known was in no way con- 
nected with his parentage. In person he was a man of 
fine appearance, and in manners plain, independent and 
sometimes rudely bluff. He was a total abstainer from 
stimulants of an alcoholic nature, lived simply, and never 
married. During his later years he maintained a close, 
though entirely honorable, relationship with the noted lit- 
térateur, Julie Jeanne Elenore de l|’Espinasse, who cared 
for him during a serious illness, and at whose early death 
he experienced a shock from which he never recovered. 
She also was without legal parentage, and though they were 
tenderly attached, and for the last seven years of her life 
were hever separated and remained unmarried, not a 
breath of scandal was ever attached to them. 

D’Alembert became a member of the Paris Academy of 
Sciences in 1741, and in 1754 of the French Academy, and 
was made its secretary for life in 1772. He was several 
times tendered the presidency of the Berlin Academy by 
King Fredrick II, and also a salary of 100,000 frances by 
Catherine II of Russia to act as tutor to her son, but de- 
clined both, being unwilling to leave the circle in Paris 
which had collected around him. There are few, if any, 
among the notables of his time, who were as highly re- 
spected for literary and scientific ability, and for the clean 
and honorable life led. 


oe 


160 Beacon Lights of Scvence 


HUTTON (1726-1797) 


GEOLOGY 


JAMES HuTTON was a native of Edinburgh, and received 
his education at the university of that city, specializing in 
law. But, after a year’s experience.as an attorney’s clerk, 
he abandoned the profession, and turned to medicine, tak- 
ing courses at Paris and Leyden. But neither did this 
occupation interest him, and in 1750, at the age of 24, he 
went back to Scotland and took up agriculture as a voca- 
tion. Through it he became interested in geology, a science 
then in its infancy—if yet born—and dominated by the 
ideas of Abraham Gotlob Werner, who occupied the chair 
of mining engineering at the famous school at Freiberg in 
Germany. This notable man was an industrious and ecare- 
ful collector and classifier of facts, but as his field of obser- 
vation was confined almost entirely to Saxony, they pro- 
vided only a limited foundation for his conclusions, which 
have not been sustained by later investigations. 

Hutton seems to have been among the first who opposed 
them, and in his ‘‘ Theory of the Earth,’’ which he read be- 
fore the Royal Society in 1785, and which was later ampli- 
fied and published in 1795 under the title of ‘‘The Theory 
of the Earth with Proofs and Illustrations,’’ he laid a firm 
foundation for the young science, by showing the errors 
of the ‘‘catastrophic’’ theories of Werner, then universally 
accepted and approved by the Church as in accord with 
the teachings of the Scriptures; and substituting in its place 
a general theory which became known later under the un- 
wieldy but expressive name of ‘‘Uniformitarianism.”’ 

This view of the past history of our planet assumes that 
its age has been enormous, its growth slow but persistent, 
and that the processes through which it has reached its 
present condition are the same as those now in operation. 
Such views naturally could not be brought into accord with 
the account in Genesis of the Creation, and when Hutton, in 
reading his paper before the Royal Society, condensed its 
concept into the phrase, ‘‘I can see no traces of a begin- 


The Exghteenth Century 161 


ning, and no prospect of an end,’’ he took a position which 
necessarily arrayed against him all the orthodox forces of 
the day. 

The result was that his theory awakened almost no re- 
sponse at the time. It was regarded as an impiety, and its 
author as an atheist. Time, however, is a corrective of all 
things. In 1802, four years after Hutton’s death, the noted 
Scotch mathematician, Playfair, boldly advocated the Hut- 
tonian theory, and shortly thereafter William Smith, the 
English geologist took the same position. 

However, it remained for Sir Charles Lyell (1797-1875), 
a man whose unquestioned attainments in other lines com- 
pelled attention, to revive the almost forgotten ideas of 
Hutton. This he did without reservation, in his great work 
entitled ‘‘Principles of Geology,’’ the first part of which 
appeared in 1830, the second in 18382, and the third in 1833. 
In this production, which is rightly regarded today as the 
most comprehensive single compilation of general geologi- 
eal data yet made, full credit is given to Hutton for having 
announced nearly half a century before, the true founda- 
tion upon which the observed facts in geology must be 
studied, if we are to succeed in interpreting them cor- 
rectly. 


HUNTER (1728-1793) 


PHYSIOLOGY AND ANATOMY 


JOHN HUNTER was born in Glasgow, Scotland, the young- 
est of a family of ten children. His primary education was 
of the most rudimentary kind, and family necessity com- 
pelled his apprenticeship in early youth to a cabinet maker. 
But at the age of twenty, with the aid of a brother who had 
become a doctor, he began the study of anatomy in the 
local hospital, and displayed so much aptitude that in 1756 
he was appointed house surgeon at St. George’s in London. 
Thereafter, his advance was extremely rapid. From 1761 
to 1763 he served as army surgeon in the wars with France 
and Portugal, and at their close opened an office in London 


162 Beacon Lights of Scrence 


for general practice, where he quickly attained so great a 
reputation for skill in the art that in 1776 he was appointed 
Surgeon Extraordinary to King George IV, which was 
probably the way in which royalties in those days paid their 
medical bills. 

Hunter is regarded as the greatest surgeon and anato- 
mist of his time. One of his most noted feats was the 
tying of an artery on its heart side for the cure of a pulsat- 
ing tumor (aneurism) which had formed in consequence of 
a weak spot in its wall. At the time it was regarded as a 
most remarkable accomplishment, and it still remains one 
of the most delicate and dangerous of operations. But he 
is best known by reason of the anatomical museum which he 
built up in London during the active years of his life. This 
contained, at the time of his death, 10,563 specimens and 
preparations illustrative of human and animal anatomy 
and physiology, and of natural history, and remains today 
perhaps the most remarkable individual collection of its 
kind in the world. Upon it he spent so freely the money 
he earned in his large practice, that he was continually in 
financial straits, and left practically no property but it at 
his death. Two years after that event it was purchased by 
the government for £15,000, and presented to the Royal 
College of Surgeons. 

Hunter published during his lifetime a number of valu- 
able monographs, among which of most importance may be 
mentioned the ‘‘History of the Human Teeth,’’ ‘‘Venereal 
Diseases’’ and ‘‘Gunshot Wounds.’’ In addition he was a 
notable contributor of papers to the ‘‘Transactions’’ of the 
Royal Society, of which he became a member in 1767, and 
from which he received the Copley medal in 1787. 


BLACK (1728-1799) 


CHEMISTRY 


JOSEPH BuAck, of Scotch-Irish ancestry, was born at 
Bordeaux, France, where his father happened at the time 
to be engaged in his business. He was educated first at 


The Exghteenth Century 163 


Belfast, then entered the University of Glasgow, and finally 
that of Edinburgh, where he took his degree in the medical 
art. Becoming first a lecturer in anatomy at Glasgow, he 
was ultimately appointed to the chair of chemistry at Edin- 
burgh where he remained during the balance of his life. 
His inclinations led to research, and resulted in several 
fundamental discoveries of importance. The most notable 
of these was the clear demonstration of the presence of the 
gas now known as carbon dioxide, as a component of those 
mineral substances called carbonates, of which limestone in 
its natural state is the most familiar example. He called 
this gas ‘‘fixed air,’’ and ascertained some of its proper- 
ties, but not its essential composition. 

The better to understand the importance of Black’s dis- 
covery, let us consider the case of producing quick (or 
caustic) lime by burning limestone in a kiln. Previous to 
his investigations it was taught by the chemists of the day 
that in the operation the fiery principle or substance called 
‘‘nhlogiston’’ entered into combination with the stone and 
imparted the heat-giving qualities to the calcined material 
when it was slaked with water. When Black demonstrated 
that the crude rock lost weight in the burning, it became 
evident that some other explanation was necessary. He 
was able finally to collect some of the escaping carbon diox- 
ide, but succeeded only in ascertaining that it differed in 
physical characteristics from atmospheric air. Between 
the years 1759 and 1763 he announced and elaborated his 
theory of ‘‘latent heat,’’ which met with almost universal 
acceptance at first, but later was shown to be merely a 
step—though an important one—towards a correct under- 
standing of the phenomena at the foundation of all exhibi- 
tions of energy. 

During the period 1766 to 1799, when he occupied the 
chair of chemistry and physies at the University of Edin- 
burgh, he published several monographs on these subjects, 
one of which entitled ‘‘Observations on the More Ready 
Freezing of Water That Has Been Boiled,’’ indicates the 
primitive state of the sciences at the time. 


164 Beacon Lights of Science 


SPELLANZANI (1729-1799) 


PHYSIOLOGY 


LAZARO SPELLANZANI was born at Scandiano in northern 
Italy, and received his education at the universities of 
Modena and Bologna. After several years of private prac- 
tice in the medical art, during which he devoted much of 
his time to private research, he assumed in 1761 the pro- 
fessorship of mathematics at Modena, and later the chair 
of natural history at Pavia, where he remained for the 
balance of his life. He was by inclination an experimental 
physiologist, and during his active years did notable work 
in enlarging and correcting current views on the subject 
ot metabolism (digestion and assimilation of food), and in 
demonstrating the falsity of the beliefs held at the time by 
many in high places as to the possibility of spontaneous 
generation. In regard to the first, the science of chemistry 
had not yet advanced to a point where the reactions that 
occur in the alimentary tract, and result in nutrition, could 
be thoroughly explained, nor those that take place in the 
lungs and cause the purification of the blood. Neverthe- 
less, enough had by then been revealed by the anatomists, 
of the nature of most of the organs of the body, to permit 
of a correct understanding of the duty performed by each, 
and it was his part to establish that the first step in 
metabolism was that of the solution of the assimilizable 
parts of food, effected at first by the combined action of 
the saliva of the mouth and the gastric juice of the stom- 
ach, and carried later to completion by the aid of solvents 
produced by the liver, the pancreas and the intestinal 
glands, by which it is finally converted into a fluid from 
which the intestines could extract those materials re- 
quired by the body for its growth and repair. In 
other words, his investigations, while not explaining the 
chemical action, did much to abolish the mystery that up 
to then had surrounded the act of digestion, and destroyed 
many of the current beliefs in which ignorance and super- 
stition had enshrouded the process. | 


The Eighteenth Century 165 


In much the same way his researches cleared the path 
for those following him on the second subject. The doc- 
trine that life (organized matter) could, in some mechani- 
cal or other way, be produced from inorganic or dead mat- 
ter, is not only a very ancient but a most natural one, and 
was held almost universally until about the middle of the 
17th century. Even since then it has been revived on 
different occasions, and by men of otherwise good standing 
in scientific circles. In fact, the tendency at the present 
time among biologists is decidedly to the effect that imas- 
much as protoplasm, at some time in the remote past, must 
have been evolved naturally out of purely inorganic ele- 
ments or compounds, in due time the chemist and physi- 
cist in collaboration, may fairly be expected to learn how to 
duplicate the feat. But in the day of Spellanzani, when 
several of the sciences were just in bud, many proofs were 
thought to have been produced of life arising spontane- 
ously from infusions of vegetable or animal matter, that 
were thought to have been perfectly protected from external 
contamination. He was among the first to investigate this 
subject exhaustively. After long boiling of his infusions, 
instead of merely corking, he fused together the necks of 
the glass flasks containing them, with the result that no 
living organisms developed. Three quarters of a century 
later as additional evidence, the German chemists, Schultze 
and Schwann, repeated the test in a different way. After 
boiling their infusions, they admitted air to them, but pre- 
viously passed it through red hot metal tubes. Under this 
treatment no life arose. Since then the matter has been 
tried out again and again in other ways, and invariably 
with negative results. So that at the present time, among 
biologists, the aphorism ‘‘no life without antecedent life’’ 
is held to be demonstrated, but with the reservation that 
some day it is not unreasonable to expect the synthesis of 
protoplasm to be effected. 


166 Beacon Lights of Science 


CAVENDISH (1731-1810) 


CHEMISTRY 


Henry CAVENDISH was born at Nice in southern 
France, of English parentage, and was educated at Cam- 
bridge, but left without taking his degree. Inheriting 
ample means, and being of a retiring disposition, he set- 
tled quietly on his estates, and devoted the entire balance 
of his life to the study of mathematics, and to experiments 
and investigations in physics and chemistry. 

In the latter department of science he made the discovery 
—very astonishing at the time—that water was composed 
of the two gases, hydrogen and oxygen, which, in his day, 
were known respectively as phlogiston and dephlogisticated 
air. 

In the department of physics, following a suggestion 
made by a clerical friend—the Rev. John Mitchell—he de- 
vised in 1798 an apparatus which enabled him to determine 
with considerable accuracy the specific gravity or density 
of the globe. This consisted of a thin and symmetrical 
metallic rod, suspended horizontally at its center by a silk 
thread, and carrying at its extremities two small balls of 
lead. When this rod came to rest its compass direction 
was accurately noted with a surveyor’s telescope. Directly 
underneath it was a revolving table or frame, the pivot 
of which coincided exactly with the prolongation of the 
suspending thread of the rod. When now larger balls of 
metal, of known weight and density, were placed on the 
table, and by revolving the latter, were brought into the 
vicinity of the small lead balls on the rod, more or less 
deflection of the latter from its compass position occurred, 
due to the mutual attraction, and the amount of this deflec- 
tion was easily measurable. With the data so supplied it 
was possible to compute the attraction that would be exer- 
cised by a mass the size of the earth, and thus determine its 
density. The figure worked out by Cavendish was 5.45, 
which is slightly below that yielded by later investigators. 
The accepted figure at present is 5.59. 


The Eighteenth Century 167 


The meaning of this figure is that the earth weighs 5.6 
as much as it would weigh if consisting entirely of water. 
Knowing its shape and dimensions, and the weight of a 
unit volume of water, it is a simple matter to arrive at the 
conclusion that its total weight is in the vicinity of 141,000,- 
000,000,000,000 tons of 2000 pounds each. 

Now it has been estimated, as the results of a large 
number of careful experiments, that the outer crust of the 
earth—say the outer 20 to 25 miles in depth of its sub- 
stance—has a density of about 2.5. If its density as a 
whole is 5.6, it follows logically that towards the interior 
the density must gradually or suddenly increase, to com- 
pensate for its comparatively surface lightness. Hence, 
it is believed that the core of the globe is a mass of metal 
which, at the exact center, probably has the density of 
the heaviest of them, uranium, which is 18.68. From the 
varying rate of transmission of the vibrations of earth- 
quake shocks around and through different sections of the 
globe, Professor Weichert has concluded that the earth’s 
core is a mass of metal 5580 miles in diameter, and of about 
the weight of iron or steel, surrounded by a stone shell 
some 930 miles thick, around which is a molten liquid or 
plastic layer of about 166 miles in thickness, extending to 
within 20 miles or so of the surface. 


PRIESTLEY (1733-1804) 


CHEMISTRY 


JOSEPH PRIESTLEY, the son of a woolen mill operative, 
was born at Fieldheld, England, and received his education 
at a Dissenters’ Academy near Northampton. Here, show- 
ing great aptitude in the languages, mathematics and 
physics, and in spite of a serious impediment in his speech, 
and a strong antipathy. to the Calvinistie brand of theology 
taught at the school, he sought the ministry as a profession, 
and at the age of 22 was at the head of a small congrega- 
tion at Needham. From there, he went as a teacher of the 
languages and belles-lettres, to an academy at Warrenton, 


168 Beacon Lights of Science 


where he married, and made his home for six years. By 
this time, in addition to an excellent knowledge of Latin, 
Greek and Hebrew, he had taught himself to read Italian, 
French and German, and ultimately acquired Chaldean 
and Syraic. These unusual linguistic accomplishments 
were recognized by the University of Edinburgh, which 
eranted him an honorary degree. 

About this period of his career, having accepted the 
charge of a chapel at Mill Hill, which happened to be next 
door to a brewery, he became deeply interested in the 
abundant gas disengaged at such places, during the fer- 
mentation of grain (now known as earbon dioxide), and 
succeeded in forcing some of it into combination with 
water. He considered it to be some kind of impure air, 
and was unable to recognize its true character. The experi- 
ence, and the interest aroused, led to other experiments. 
One of these had to do with the red oxide of mercury, a 
fairly well-known substance at the time, which occurs in 
nature as the mineral cinnabar, and from which the metal 
is easily reduced by heat. Priestley succeeded in effecting 
this reduction with a burning glass, and in collecting some 
of the escaping oxygen, which he ealled ‘‘dephlogisticated 
air.’’ But while he noted some of its remarkable proper- 
ties, it remained for the chemist, Steele, a few years later, 
to isolate it in larger quantities, and to announce its real 
character. 

So far as known this was the first case of the isolation 
of this element (the most abundant in nature), and its 
recognition at this time (1774) was an event of primary 
importance in the development of science. It may be said 
to mark the birth of chemistry, and the death of the phlog- 
iston theory, which up to that time had been generally ac- 
cepted. 

The discovery so enhanced the reputation of this versa- 
tile man, that he was offered the post of ‘‘literary compan- 
ion’’ to Lord Shelbourne, and accompanied him on a jour- 
ney through France, Holland and Germany. In 1777 he 
wrote and published a pamphlet entitled ‘‘Disquisitions 
Relating to Matter and Spirit,’’ a production which had 


The Exghteenth Century 169 


neither scientific nor religious value, even for its time, and 
was so repugnant to the orthodoxy of the day, that his 
relations with Lord Shelbourne were terminated. In 1780 
he became the minister of a dissenting congregation at 
Birmingham, and preached there for three years. Finally, 
to escape persecution for his religious views, he emigrated 
to America, settling at Northumberland, Pa., and remained 
there until his death. 

Priestley was a brilliant but also an erratic character. 
With vast learning, and a vivid imagination, was coupled 
a visionary temperament which constantly led him astray. 
Yet he fully deserves the credit of being the first to isolate 
the most abundant of the elements, and the one which plays 
the most important part in the maintenance of animal and 
vegetable life on the globe. 


COULOMB (1736-1806) 


PHYSICS 


CHARLES AUGUSTIN DE COULOMB was born at Angouléme, 
France, and after receiving a good education in the funda- 
mentals, entered military life, and became an officer in the 
engineering corps of the army. Becoming interested in the 
phenomena of magnetism and electricity he studied the lit- 
erature of those rapidly growing departments of science, 
and in 1777 was awarded a prize for an essay on the con- 
struction of magnetic needles. In 1779 he gained another, 
for a monograph on the theory of prime movers, and in 
1781 a third for a paper on the subject of friction. These 
so established his reputation as a scientist of ability, that 
he was elected a member of the French Academy of Sci- 
ences, and called upon to solve a number of difficult prob- 
lems in mechanical engineering. 

His great accomplishment was that of the adaptation of 
the torsion balance (designed by John Mitchell, and per- 
fected by Henry Cavendish, and employed by the latter to 
measure the force of gravitation), to the measurement of 
the strength and action of magnetic poles. For this pur- 


170 Beacon Lights of Science 


pose a long and thin magnet was suspended at its central 
point on a fine wire, the torsional capacity of which had 
been previously determined), so that it could revolve freely 
in either a horizontal or vertical plane. A similar magnet, 
suspended at one of its ends, was then placed near one of 
the poles of the other. The strength of the reaction result- 
ing could then be determined by noting the angle through 
which it was necessary to turn the head screw carrying the 
wire for the horizontally disposed magnet, to maintain it in 
its original position. For this service to science, his name 
was adopted by the International Scientific Association, as 
the unit of that quantity of electricity which passes through 
a conductor of unit size in a second of time, an honor which 
will keep his memory alive as long as the electrical science 
endures. 

While the phenomenon called magnetism is now recog- 
nized as one of the manifestations of that universal force 
which, in other aspects is exhibited to the senses as light, 
heat, electricity, ete., its cause is not yet completely ac- 
eounted for. The latest theory on the subject is that of 
the English physicist, J. J. Thomson, who suggested that 
it might be explained by the rotation of the molecule, with 
its Faraday tubes connecting the atoms. Further light 
however is necessary. 

Who first observed the properties of the natural magnet 
is unknown, though it has been recognized as a fact for at 
least three thousand years. The substance itself is techni- 
eally known as the feroso-ferric oxide of iron, or the per- 
oxide (Fe,0,), consisting of 72.4 per cent of the metal, and 
27.6 per cent of the gas oxygen. It is black in color and 
abundant in nature, constituting, in fact, one of the im- 
portant ores from which the metal is obtained. It occurs 
mainly in those oldest of the rocks that are grouped by the 
geologists as predominant in Archean time. The first lit- 
erature on the subject was a book entitled ‘‘De Magnete’’ 
written by William Gilbert (1540-1603), in which he col- 
lected all the facts and fancies current up to that date on 
the mysterious properties of the natural lodestone. 


The Exghteenth Century 171 


WATT (1736-1819) 


MECHANICS 


JAMES WATT, who was born at Greenock in Scotland, is 
often credited with the invention of the steam-engine. But 
the principles underlying its construction had been known 
for centuries before his time, and even before his birth 
engines of a sort were in operation in Cornwall. Neverthe- 
less, to his genius and industry the world is indebted for 
vital improvements in their construction, without which 
the machine would never have amounted to much as a 
producer of power. 

The earliest known application of steam to produce 
motion was that made by Hero of Alexandria, an Egyptian 
mathematician and mechanic living in the first or second 
century of the present era, who devised what he called an 
aeolipile. It consisted of a hollow metallic globe mounted 
on trunnions, and provided on opposite sides with tubular 
arms curved in opposing directions, each terminating in a 
small opening. When the globe was partly filled with 
water and heat applied, the escaping steam, reacting 
against the air, caused it to revolve. In 1629 an Italian 
named Branea made a windmill turn by projecting a jet 
of steam against its vane and may thus be regarded as the 
originator of the steam turbine idea. In 1698 a patent. was 
seranted to one Thomas Savery in England for a device in 
which steam was employed to raise water out of a forty-foot 
mine shaft in Cornwall, but no clear description of its 
mechanism has been preserved. It is generally agreed that 
to the Freneh physicist Denis Papin belongs the credit 
(in 1690) of employing steam on one face of a piston con- 
fined in a cylinder, and of condensing the vapor at the end 
of the stroke by a jet of water, the piston then falling back 
to its initial position by its weight. The next step was 
taken in 1705 in the construction of the Newcomen engine, 
where the cylinder was mounted vertically over the boiler, 
and connected with it by a pipe fitted with a stop cock, 
which was manipulated by an attendant—generally a boy. 


172 Beacon Laghts of Science 


One of these youngsters, named Humphrey Potter, devised 
a combination of levers and cords attached to the piston rod 
by which, with improvements made later by the engineer, 
Henry Brighton, a fairly self-acting machine resulted. 
These, for more than the following fifty years, were quite 
extensively employed in the mining districts. 

It was at this stage of its development that Watt’s atten- 
tion was drawn to the machine, and his work on it began. 
His first improvement was to arrange for the condensation 
of the steam outside of the cylinder, and in a chamber 
where a vacuum could be maintained. This was followed 
in turn by the introduction of the steam on both sides of 
the piston, which permitted the cylinder to be placed in 
a horizontal position if desired; the use of the steam 
expansively, and the employment of the flywheel to convert 
reciprocating into rotary motion. Confronted with a pat- 
ent on the connecting rod or crank, that had been granted 
to a former employee—though Watt claimed to have 
originated the idea—he invented what became known as the 
‘“sun and planet gear’’ which answered well as a substitute. 
After these, he contributed the governor, the water and 
mercury steam gauges, and a number of other minor but 
important improvements. So great was the confidence 
inspired by his mechanical ingenuity that he had no diffi- 
eulty in securing the capital required to embark extensively 
in the manufacture of engines; and when he retired in 
1800, he was able to turn over to his two sons a large and 
highly remunerative business. 

In 1784 he was elected a member of the Royal Society 
of Edinburgh, and in the following year of the Royal 
Society of London. In 1806 the degree of LL.D. was con- 
ferred on him by the University of Glasgow, and two years 
later he was made a foreign associate member of the French 
Institute. After his death a national memorial in his honor 
was placed in Westminster Abbey, and a fine statue, paid 
for by popular subscription, erected in Birmingham. 


The Eighteenth Century 173 


LAGRANGE (1736-1813) 


PHYSICS 


JOSEPH Louis LAGRANGE, although of French parentage, 
first saw the light in Turin, Italy, when the province of 
Piedmont in which it is situated was part of France, was 
the son of the war treasurer of the King of Sardinia, and 
was educated at the college of his native city. At an early 
age he exhibited unusual mathematical ability, and was 
able in his nineteenth year to send to Euler, the Swiss 
mathematician, a correct solution of what was known at 
that time as the isoperimetric problem, which he accom- 
plished by supplying a notation for an extension of the 
principles of the calculus of variations. This notable step in 
the growth of the science gave him such a reputation among 
European mathematicians that he was offered the chair of 
mathematics in the military school at Turin. 

In 1758 he founded the Royal Academy of Turin. In 
1764-1766, as the result of studies on the phenomenon of the 
librations of the moon, and the system of Jupiter and its 
satellites, he succeeded Euler as director of the Academy 
of Berlin, and remained there until 1786, when he removed 
to Paris, and was elected a member of the French Academy. 
Upon the establishment of the Ecole Polytechnique he be- 
came one of its professors, and later received a similar 
appointment in the Ecole Normale. When Napoleon came 
into power he was given the rank of count, and became a 
member of the Senate. His most notable writings were 
‘‘Mécanique Analytique’’ (1788), and ‘‘Théorie des Fone- 
tions Analytique’’ (1799). These, added to many other 
studies in the science of numbers of lesser note but of un- 
doubted value, established his standing as perhaps the 
greatest of all pure mathematicians of his day. 

The accomplishment which entitles him to be regarded as 
one of the notable discoverers in the realm of the sciences 
was his development of the principles of ‘‘virtual veloci- 
ties,’’ a phrase or expression coined by Jean Bernouilli in 
1717, most unfortunately, for it has nothing to do with 


174 Beacon Lights of Scrence 


velocities as the word is ordinarily used. The principle, as 
now understood, is as follows: 

‘‘Tf a body is in equilibrium, the sum of all the forces, 
each multiplied by the practical velocity of its point of 
application is, for every possible infinitesimal displacement 
of the body, equal to zero.’’ 

Expressed in this way the principle is not easy of com- 
prehension. Perhaps the simplest illustration of the idea 
back of the phenomenon is to be obtained from the action 
of the movable pulley where, if the force applied to the 
cord (like a weight) moves down a certain distance, another 
weight fastened to the pulley must move up such a dis- 
tance, that the product of each weight by its distance is 
the same. 


GALVANI (1737-1798) 
ANATOMY 


LuIG!I GALVANI was a native of Bologna, Italy, and was 
destined by his parents for the Church. But, preferring 
medicine, he made himself so proficient in that art, that he 
was offered and accepted the chair of anatomy at the uni- 
versity of his native ctiy, and while there published a 
number of valuable monographs on anatomical and surgi- 
eal subjects. 

In 1786, while studying the muscular system in the legs 
of frogs, he had suspended several freshly prepared speci- 
mens by wires alongside of the iron framework of a bal- 
eony, and his attention was attracted to the fact that when 
(moved by the wind) one of them touched the iron, the 
muscles contracted strongly, as if still alive, the action 
being repeated at each contact, until decomposition of the 
flesh had begun. He correctly ascribed the effect to a force 
traversing the nerves, but assumed its origin to be in the 
leg of the animal, and an indication of the existence of a 
vital force, and hence of the continuance of life for a con- 
siderable period after apparent death and dismemberment. 
This explanation of the phenomenon was later shown by 
Volta to be an error. 


The Exghteenth Century 175 


Aside from this more or less accidental discovery, Gal- 
vani made no other notable contribution to the advance- 
ment of science. But in the fields of anatomy and medi- 
cine his standing was so high, that in 1879 a long-overdue 
statue was unveiled to his memory in his native city. 

The rather startling nature of his discovery, and the per- 
sistence through many years (as a result of his great medi. 
cal reputation) of his theory of a ‘‘vital force,’’ has won 
for his name a very extended notoriety. Thus, even today, 
we speak of the galvanic current when we should eall it 
the voltaic current, and similarly we use the term galvani- 
zation in referring to the effects of the voltaic current as 
displayed in the various processes of metal plating. But 
Volta has been properly honored in another way. How- 
ever, when we speak of an individual as having been gal- 
vanized into a temporary or fictitious display of activity, 
we correctly recall to mind the picture of Galvani’s frogs’ 
legs hanging on his baleony, and exhibiting unsuspected 
and adventitious indications of life. 


HERSCHEL (1738-1822) 


ASTRONOMY 


WILLIAM HERSCHEL, the son of a musician, resided in 
Hanover, Germany. Expecting to follow the profession of 
his father, he was given a thorough musical training, in 
addition to the general education of his day. At the age 
of nineteen he moved to Leeds in England, and became a 
teacher of the art. After a few years there he secured a 
position at Halifax as organist, and in 1766 undertook the 
same kind of work at Bath. Here he became interested 
in astronomy, and being unable to purchase a telescope, 
he made one of five foot focal length. With this, in 1781, 
he discovered the planet Uranus, till then unknown, which 
brought him so much favorable notoriety, that he received 
and gladly accepted an offer from the King (George IIT) 
to become his personal astronomer. He set up his instru- 
ments at the little village of Slough in the vicinity of 


176 Beacon Lights of Science 


Windsor, where (as now) was the residence of the ruler. 
Here, assisted by a younger sister Caroline, who had previ- 
ously joined him at Bath, he remained for the balance of 
his life, engaged mainly in observational work, but also in 
the manufacture of mirrors for reflecting telescopes, of 
which he made a speciality, regarding them superior to the 
refracting variety. Here also he married, and having be- 
come rich thereby, as well as securing a life partner who 
was as thoroughly interested as his sister and himself in 
the study of the heavens, he began, in 1785, the construc- 
tion of what was for its time, the largest and most powerful 
telescope in the world. Its mirror was 48 inches in diam- 
eter, and its focal length 40 feet. With this tremendous 
engine of discovery, and aided by his highly gifted sister, 
the two made a marvelous record in observational work, 
including the discovery of six satellites of Uranus, two 
(the 6th and 7th) of Saturn, the establishment of the ro- 
tational periods of Saturn and Venus, the first of binary 
stars, the location of over 2300 new nebulae, many remark- 
able studies of the Milky Way, and a voluminous catalogue 
of double stars. 

It is not too much to say that the work of this notable 
pair of observers—devoted tenderly to each other, as well 
as heartily to their vocation—led to a comprehension of the 
immensity and wonders of the Universe, which had not 
previously been attained even by the greatest of their prede- 
cessors. 

Herschel received the honor of knighthood from the 
King, and the degree of D.C.L. from the University of 
Oxford. He contributed 69 original papers to the Transac- 
tions of the Philosophical Society, and to the first volume 
of the Memoirs of the Astronomical Society a paper en- 
titled ‘‘On the Places of 145 New Double Stars.’’ His 
sister Caroline, on her completion of the catalogue of nebu- 
lae and star clusters detected by herself and her brother, 
was elected an honorary member of the Royal Society, and 
was presented with its gold medal. On the death of her 
brother she returned to her native land. 


The Eighteenth Century 177 


SCHEELE (1742-1786) 


CHEMISTRY 


CarL WILHELM SCHEELE was born at Stralsund, Sweden. 
Of his early life almost nothing is known. But at the age 
of twenty-five he opened an apothecary shop at Stockholm, 
and three years later moved to Upsala, presumably on ac- 
count of the advantages to be gained at the university 
there, in prosecuting his studies in chemistry, which had 
begun some years previously, and for which he must have 
had some preliminary training. Whether this was the case 
or not, he quickly became known as the discoverer of a 
number of elements and compounds that proved to be of 
importance in the rapidly growing arts of his day. 

The first of these was tartaric acid, a compound of car- 
bon, oxygen and hydrogen which occurs abundantly in the 
vegetable world, and particularly in that product of the 
fermentation of grape juice which is known as argol. This 
substance had of course been known for centuries, and 
from it the commercial product called tartar and cream 
of tartar was prepared, consisting essentially of a combina- 
tion of the tartrates of potash and lime. But the acid itself 
had never been isolated. That feat Scheele accomplished, 
recovering it in the form of colorless transparent crystals 
which, many years later, were found to possess the very 
eurious property, when gently warmed, of becoming 
strongly electrified, the opposite sides of each crystal ex- 
hibiting the opposite states of that form of energy. He 
made no attempt to resolve this new compound into its 
component elements and, in fact, none of the three were 
then even known, except hydrogen, which went under the 
name of phlogiston. 

His next important discovery, in 1774, was the gas chlor- 
ine, which he called ‘‘dephlogisticated marine acid gas,’’ as 
he recovered it from sea salt. He did not become aware of 
its elementary character, and it was not until Davy, thirty 
years later, isolated it, that it was given the name it now 
bears. In the same year Scheele produced baryta for the 


178 Beacon Lights of Science 


first time. He extracted it from the mineral witherite, 
but did not push his investigation any further. It was to 
him simply a new substance. But again Davy, in 1808, 
following his lead, and using a powerful voltaic battery, 
separated the metal barium from it, and proved its ele- 
mentary nature. 

In 1775 he discovered the gas oxygen, without the knowl- 
edge that it had been discovered by Priestley in 1774. 
Scheele gave it the name of empyrial air. A little later the 
name of ‘‘vital air’? was suggested for it, because not only 
could it be breathed to a limited extent with impunity, but 
when inhaled caused a wonderful sensation of exhilaration. 
Its true character as an element was demonstrated later by 
Lavoisier, who also gave it its present name. Finally, in 
1770, Scheele produced accidentally in his laboratory a 
syrupy liquid with a sweet taste, which he called glycerin; 
and shortly thereafter, in much the same way, the highly 
poisonous compound hydrocyanic acid, which was popu- 
larly known in his time as prussie acid. In neither case 
was he able to determine its ultimate composition. Both 
of these substances are of importance in the arts, especially 
elycerin, which was thoroughly investigated by Chevreul. 

Seheele was in no sense a chemist. In fact, that science 
had hardly come into existence in his time. But he was an 
earnest and tireless investigator of the alchemistie order, 
and while practically all_his discoveries were chance ones, 
he deserves the eredit for them. His position in the prog- 
ress of science may be compared to that of the scout who, 
in the field, travels in advance of the main body of ex- 
plorers, reconnoitering the country,-and every now and 
then stumbling on a fact or principle which proves to be of 
importanee when further examined by the investigators 
following. It was just in such a way that he happened to 
encounter that compound of arsenic and copper which is 
still known commercially as ‘‘Scheele’s Green,’’ and which 
is extensively used in the arts connected with the produc 
tion of wall paper and printed ealico. 


The Exghteenth Century 179 


HAUY (1743-1822) 


MINERALOGY 


RENE Just HAtiy, a native of the little town of St. Just 
in France, was educated for the Church and took priestly 
orders. But, while teaching theology in Paris he became 
deeply interested in botany, as a result of attending the 
lectures of the noted naturalist, Dauberton. Sometime 
afterwards he happened to be handling a crystal of calcite, 
which dropped from his grasp and broke into fragments 
on the stone floor. While gathering these up he noticed 
that each fragment was, in its way, a crystal of the same 
form as that of the original. This interested him so greatly 
that he began the study of crystals of other minerals. Be- 
ing a patient and keen observer he continued research in 
this branch of natural phenomena and became practically 
the founder of the science of crystallography, a department 
of knowledge which, since his day, has expanded and led 
to many important results in industry. In 1793, after the 
Revolution—during which he suffered imprisonment and 
came near to losing his life—he was appointed a member 
of the Commission on Weights and Measures, and in the 
following year became keeper of the Cabinet of Mines. In 
1802 he was elected professor of mineralogy at the Museum 
of Natural History in Paris, to which institution he willed 
his remarkable collection of erystals. The beautiful and 
rather rare mineral ‘‘hauynite’’ (or hauyne as it was first 
called), a sodium, calcium and aluminum silicate and sul- 
phite, pleochroic and generally found only in eruptive 
rocks, was named in his honor. Haiiy (whose name is pro- 
nounced in French as if spelled ‘‘a-we’’) became a mem- 
ber of the French Academy, and published several books 
on his specialty, which are classic. In these he advanced 
the theory (which has since held good) that erystalline 
form should be the prinicipal element in the determination 
of a mineral. 

Tnorganic—that is, non-vitalized—material, when in the 
solid state, appears in nature in two ways, either as a 


180 Beacon Lights of Science 


erystal or as an amorphous body like a mass of glass which, 
in cooling, will take any shape desired. Hach member of 
the first category has its own habit of body making. The 
eause back of this seems to be a definite property of the 
unit molecule, under the impulse of which, when an assem- 
blage of one kind is gathering, each one will dispose of 
itself along certain lines and in certain invariable direc- 
tions if free to do so. Why this is the law is, as 
yet, one of the unsolved problems of science, which the 
crystallographers deprive of some of its mystery by 
alleging varying ‘‘coefficients of expansion’’ in each kind 
of molecule. At times such substances are found to be 
apparently arranged otherwise, showing no faces, bounding 
lines or angles of crystals to the eye, or even under the 
microscope. This condition is the result of the crowding 
by each other while in the act of growing in a confined 
space. Under such circumstances the substance is capable 
of exerting enormous force in following out the law of its 
being, as is well known in the case of water freezing. Mas- 
sive quartz is another good illustration. Even here the un- 
known force or habit or property has not been absent dur- 
ing the process of solidification. This may be demonstrated 
by means of a sphere cut from an apparently amorphous 
mass of such material. When heated it will become dis- 
torted, expanding in several directions and more in one 
than in another, with the result that the figure will become 
a spheroid. Whereas a globe of glass when given the same 
treatment will retain its spherical shape. 

Crystallography is one of the exact sciences, with 
limited capacities, and these based upon mathematical laws. 
As knowledge in its phenomena increased, its devotees set 
to themselves the task of determining how many points in 
space were possible, under certain assumptions based on 
properties known by observation to be common to all erys- 
tals. It was found that only 32 could exist. Of these, 23 
had already been recognized, and 6 more were found 
shortly thereafter. Probably the remaining 3 have since 
been located in nature. All so far detected correspond ab- 
solutely with the theory underlying the system. These 


The Exghteenth Century 181 


32 kinds of known and possible crystal symmetries are now 
srouped under six systems, into one of which every known 
or conceivable form of that kind of entity can be gathered. 
The recent employment of erystals of the metallic minerals 
in radio installations, has resulted in arousing renewed in- 
terest in this beautiful and somewhat neglected field of 
nature. 


LAVOISIER (1743-1794) 


CHEMISTRY 


ANTOINE LAURENT LAVOISIER was a resident of Paris, 
and educated at the Collége Mazarin. He developed at an 
early age unusual mathematical capacity, and became also 
deeply interested in the science of physics. In 1768 he was 
elected a member of the Academy of Sciences. In the fol- 
lowing year he was appointed to the governmental position 
called a ‘‘farmer general of the revenue,’’ which yielded a 
good income, and at the same time enabled him to devote 
his attention to researches in science. In 1776 he added to 
his publie duties the directorship of the national gunpow- 
der factory, where he introduced several valuable improve- 
ments. In 1778 he was appointed one of the trustees of 
the Bank of Discount, and in 1790 became a member of 
the Commission on Weights and Measures, taking a promi- 
nent part in the movements which finally resulted in the 
establishment of the Metric System, now universally em- 
ployed in scientific measurements, and in common usage 
throughout the civilized world except among the Anglo- 
Saxon nationalities. 

When the French Revolution broke out Lavosier, as a 
member of the aristocracy, as well as the holder of several 
positions under the government, became obnoxious to the 
proletariat, and in 1794, along with twenty-six other revenue 
collectors, was guillotined under the accusation of Dupin, 
a member of the Convention, as ‘‘one of the enemies of the 
country.’’ Desperate efforts were made by friends to save 
his life by urging his high professional rank and services. 


182 Beacon Laghts of Science 


But to all these the only reply of the Tribunal was, ‘‘We 
need no more scientists in France.’’ 

Lavoisier is regarded as the founder of the modern sci- 
ence of inorganic chemistry. Although, at the time, the 
principle of the indestructibility of matter—or the Conser- 
vation of Mass—had not been grasped as a whole by scien- 
tists, any more than the similar principle of the indestruc- 
tibility of foree—Conservation of Energy—yet he became 
aware, in his chemical work, of the fact that in all his 
experiments, whatever changes in kind occurred, if all the 
products of these changes were preserved, their combined 
weight exactly equaled that of the original substance under 
investigation, plus the weight of all reagents employed and 
retained, and demonstrated the fact by introducing the 
balance into his laboratory, and the principles of mathe- 
matics as its fundamental tool. 

This idea, when once accepted, transformed the crude 
chemistry of the day into an exact science, and was quickly 
followed by the development of a system of nomenclature 
devised in collaboration with Berthollet and others, which 
was substantially identical with that employed ever since. 

Lavoisier produced, during his comparatively brief career, 
a large number of scientific papers, the most of which were 
on purely chemical subjects. It will be interesting to note 
that in one of them he gave a list of the 33 elementary 
substances accepted as such at the time, two of which were 
ealoric and light. At present 88 are known, and among 
them caloric and light do not appear. 


LAMARCK (1744-1829) 


NATURAL HISTORY 


JEAN BAPTISTE PIERRE ANTOINE LAMARCK was born at 
Bazintin-le-Petit in France. His parents designed him for 
the Church and entered him at the College of the Jesuits 
at Amiens; but at the age of sixteen he left the institution, 
enlisted in the army, distinguished himself, and rapidly 
rose to a lieutenancy. Being compelled to give up military 


The Eighteenth Century 183 


life on account of an accident that disabled him physically, 
he went to Paris and began the study of medicine. From 
this he became interested in botany, and placed himself in 
the employ of Bernard de Jussieu, under whose guidance 
he studied that science for ten years. In 1778 he published 
his first work entitled ‘‘Flore Franeaise,’’ which was so 
well received that in the following year he was elected a 
member of the French Academy of Sciences, and two years 
later appointed Royal Botanist, commissioned to travel in 
foreign lands, and to investigate foreign public and private 
botanical collections. After reporting on those in Holland, 
Germany and Hungary, he was appointed in 1783 keeper 
of the Royal Gardens at Paris, which later became the 
famous Jardin des Plantes. This he built up into an insti- 
tution of the highest order and service. After serving there 
for ten years, he was tendered the chair of invertebrate 
zoology at the Museum of Natural History at the capital, 
and retained his connection with it in various capacities 
for the remainder of his active life. In the years between 
1815 and 1822 his principal work entitled ‘‘ Natural History 
of the Invertebrates’’ was published. This, years after his 
death, gained him immortal renown, for in it he enunciated 
certain principles which are fundamental in the theory of 
evolution, as later worked out more thoroughly and cor- 
rectly by Darwin. 

Lamarck was a man of keen and broad observational 
powers, but in no sense an experimenter. He lacked the 
patience to collect, compare and test, which characterized 
the work of Darwin. Hence, though he held and expressed 
in his writings advanced views on many departments af 
Science besides botany and zoology—including chemistry, 
meteorology, physics and geology—many of his conclusions 
have not been sustained, and so his general standing as a 
scientist has suffered. Nevertheless, he is fully entitled to 
rank as the founder of the science of invertebrate paleon- 
tology, and was among the first after Hutton to assert the 
great length of geologic time, the continuous persistence of 
organic life throughout the geologic periods, and the influ- 
ence of environment on habits and physical modifications. 


184 Beacon Laghts of Science 


In the domain of chemistry and physics his speculations are 
of little account. From 1799 to 1810 he published annually 
a meteorological report, and was the first to attempt to 
foretell weather probabilities, but only of a general or 
seasonal kind. The latter third of his long life was sad- 
dened by bereavement and scarcity of means, and the final 
ten by blindness, compelling him to work with the aid of 
his daughter Cornélie as an amanuensis. But to the last 
he maintained his courage, his high standard of honor, and 
his imperturbability under misfortune. No finer charac- 
ter is to be found in the annals of science. 


VOLTA (1745-1827) 


ELECTRO-CHEMISTRY 


ALESSANDRO VoutTa lived at Como, in Italy. After re- 
ceiving a good general education, he became deeply inter- 
ested in the investigation of the phenomena of electricity, 
which were then just beginning to attract the attention of 
students throughout the educated world. In 1774 he was 
appointed to the chair of natural philosophy in the gym- 
nasium at Como, and in 1779 was advanced to a professor- 
ship at the University of Pavia. 

When Galvani, in 1790, announced his explanation or 
theory of the phenomena of the frogs’ legs as an exhibition 
of a new force, which he called the ‘‘vital foree,’’ or ‘‘ani- 
mal electricity,’’ Volta took issue with him, claiming that 
the current exhibited in the batrachian’s legs originated 
in the two metals involved, and not in the muscles or nerves 
of the animal. Not possessing at that time the high stand- 
ing of a man of science that Galvani commanded, not much 
attention was paid to his theory. But by 1800 he had con- 
structed what was at first called Volta’s ‘‘ecrown of cups,’’ 
and later known as the voltaic pile. As originally made, 
the device consisted of disks of two different metals (zine 
and copper), arranged in couples, each couple separated 
from the one above and below it by a disk of cloth mois- 
tened with a weak solution of common table salt. Then, 


The Exghteenth Century — 185 


when the upper member (copper) of the couple at the top 
was connected with the lower member (zine) at the bot- 
tom of the pile, by a copper wire, an electrical current was 
set up which could be felt, or made to ring a bell. When 
the details of this experiment came to the ears of Sir Hum- 
phry Davy, he is said to have remarked that ‘‘the voltaic 
battery was an alarm bell to experimenters in every part 
of Europe.”’ 

It was quickly shown that Volta’s explanation of the 
cause of the current was no more correct than that of Gal- 
vani. For, when the metal couples were placed in cups—or 
cells as now designated—and connected up, and a weak 
solution of acid in each cell took the place of the cloth 
moistened with salt, not only was the current much 
stronger, but chemical action began, which plainly was the 
cause of the current. Several years elapsed before it was 
clearly understood just what was taking place, but by 1802 
water had been decomposed by the current into its two 
constituent gases (hydrogen and oxygen), and in 1807 the 
first electric are light was produced, in both cases the cur- 
rent coming from a large and powerful voltaic battery. 
This was the beginning of the science of electro-chemistry, 
which now plays such an important part in innumerable 
modern industries, where vast amounts of capital are in- 
vested. 

Volta is also remembered as the inventor of the electro- 
phorus, the condensing electroscope, the electrometer, the 
electric pistol, and the electric lamp. All these, in the form 
he gave them, would now be regarded more as toys than as 
scientific tools, for in his time, and for many years after 
it, electricity was regarded as a kind of fluid. Neverthe- 
less, So remarkable were the manifestations resulting from 
his crude experiments that his name has been justly hon- 
ored in the realm of the science, by adopting it (the volt) 
as the unit of electro-motive force, and he is properly re- 
garded as the father of the science of electro-chemistry. 


186 Beacon Lights of Science 


CHARLES (1745-1823) 


AERONAUTICS 


JACQUES ALEXANDRE CESAR CHARLES was a native of 
Beaugency in northern France, was well educated in fun- 
damentals, and became an experimental physicist of note, 
His claim for honorable mention in the domain of science 
rests upon the fact that he was the first to use hydrogen 
to inflate balloons, and also the first to make a public ascent 
in one so filled. On the occasion, on December 1, 1783, he 
attained an altitude of 7000 feet. 

There are no records of attempts at aviation among the 
ancients, though the Greek myth of Daedalus, who made 
wings of feathers cemented together with wax for himself 
and his son Icarus, and endeavored with that fragile equip- 
ment to escape from his Cretan captor, King Minos, shows 
that these imaginative people did some thinking on the sub- 
ject. As the story is told, Daedalus succeeded in crossing the 
sea, and landing in Italy. But Icarus, in his youthful exu- 
berance, mounted to such an altitude in his flight, that the 
heat from the sun was too much for the wax of his wings. 
When they collapsed, he fell into the sea and was drowned. 
From this pretty tale it may be inferred that the Greeks be- 
lieved the sun to be but a short distance above the earth; 
and also that as a people they were not much given to 
mountaineering. For if they had been, they would have | 
become acquainted with the fact that as altitude is gained 
the temperature of the air rapidly declines. 

There are authentic records of attempts—which usually 
resulted disastrously—of gliding flights, during the Middle 
Ages; but they appear to have amounted to nothing; and 
it was not until the chemist, Cavendish, in 1766, succeeded 
in isolating the gas hydrogen by the electrolysis of water, 
and demonstating its extraordinary lightness, that interest 
in the subject of aviation revived with the experiments 
made by Cavallo, who filled bladders and paper bags with 
the gas, and succeeded in making them rise to the ceiling 
of a room. But in both cases the material proved to be 


The Eighteenth Century 187 


so porous, that they sank quickly. The idea was then taken 
up by the Montgolfier brothers at Annonay in France, who, 
in June, 1773, after many trials, made a balloon 35 feet 
in diameter and filled with hot air, rise to a height of 
1600 feet. When the news of this extraordinary event 
reached Paris, a subscription was at once taken up to 
raise means for a repetition of the experiment there under 
better conditions. The construction of the bag was en- 
trusted to a firm of instrument makers of high reputation, 
and of the hot air to Charles, who had become known as 
a physicist of consequence. He determined to employ the 
newly-discovered gas hydrogen—then called ‘‘inflammable 
air’’—for inflation, and after nearly a week of laboratory 
work, manufactured enough of it to fill a bag 12 feet in 
diameter, which had been constructed of silk covered with 
a flexible gum or varnish. This was taken to the Champs 
de Mars, and on August 27, 1773, in the presence of an 
enormous crowd, the balloon was cut loose and disappeared. 

In September of the same year the Montgolfiers built a hot 
air captive balloon 72 feet high and 41 feet in diameter, 
which ascended successfully, but was destroyed when it was 
up by a heavy wind, followed by rain. A second one of 
nearly the same dimensions, to which was attached a basket 
containing a sheep, a cock and a duck, was sent up a week 
later, and after remaining in the air for about a quarter 
of an hour, was drawn to earth without injury to its in- 
voluntary passengers. 

In November of the same year in another hot air balloon, 
74 feet in height and 48 feet in diameter, to which a strong 
wicker work basket was attached, the first ascent by a 
human being (Pilatre de Rozier), was made. This one re- 
mained afloat for twenty-five minutes, sailed across the 
Seine, and finally came to earth without injury to its 
plucky occupant. In the following month, Charles, using 
a hydrogen-filled silk bag, and carrying a barometer, made 
the ascent to the great height mentioned. So intense was 
the interest excited by this event, that the sport was taken 
up by a number of enthusiasts, one of whom by the name 
of Blanchard, accompanied by an American named Jeffries, 


188 Beacon Lights of Scvence 


successfully crossed the English channel from Dover to 
Calais early in the year 1785. In 1795 the first descent in 
a parachute was accomplished. 


MONGE (1746-1818) 


MATHEMATICS 


GASPARD MoNGE was a resident of Beaune in France. He 
was educated there, and at Lyons; and for a time taught 
physics and mathematics. Later he studied at the engineer- 
ing school at Méziéres, then became a tutor, and finally 
rose to the professorship of mathematics. In 1783 he was 
appointed examiner of naval pupils in Paris, and in 1792 
became Minister of the Marine. In 1806 he was raised to 
the nobility, with the title of Comte de Pelouse. 

He is regarded as the founder of the science of descrip- 
tive geometry, and of the modern system of teaching it. 
He introduced into the analytic geometry of three dimen- 
sions, a thorough treatment of linear equations; completed 
the study of surfaces of the second degree that had been 
begun by Euler, and established the principles of the inte- 
eration of partial differential equations, in connection with 
the theory of surfaces. 

Descriptive Geometry is that branch of the science which 
teaches methods of representing bodies of three dimen- 
sions—a cube, a bridge, a piano, ete.—on a flat surface, 
so that the effect produced in the mind of an observer is 
not that of a diagram, but of an outstanding object, cast- 
ing shadows as does the real one of which it is the repre- 
sentation. Of course any one properly trained in the art 
of drawing, or possessing the faculty naturally, can pro- 
duce this effect approximately; but to do so with mathe- 
matical accuracy a knowledge of the laws of perspective 
are necessary. The fundamentals of these are first, a base 
line, which limits the extent of the picture in the direction 
of the maker thereof, and is oftener called the ground line; 
second, the horizon line, which limits its extent in distance; 
third, the vertical line, which is at right angles to the other 


The Eighteenth Century 189 


two, is not put on the paper, and need not be in the center 
of the picture, but is supposed to pass through the eye of 
the sketcher, and thus to constitute the point of sight or the 
center of the drawing. ‘To it, all the vertical lines in the 
object being depicted must be parallel. The horizon line 
is generally set at about one-third of the height of the 
drawing. If the artist is sitting, this line will fall some- 
what below that height. If he is standing it will rise 
slightly above it.. In addition, are two points called points 
of distance, situated on the horizon line, one of them to the 
right of the vertical line, and the other to the left. If the 
object to be depicted is to be placed in the position called 
a half front or half profile, the distance of these two points 
from the vertical line is equal, but if the object is depicted 
as if in the three-quarter (or greater) position, one of them 
is farther away from the vertical line than the other, the 
most distant being on that side on which the largest area 
of the object is to be shown. 

These points having been set, they now become what are 
called the vanishing points. To one of them—the most 
distant—all lines excepting verticals appearing in the front 
or face of the object must point, and to the other all lines 
appearing on its sides (or thickness, or depth). If these 
rules are followed in the process of representing any sym- 
metrical body such as a building, the result will be found 
to correspond with the impression of it which the eye car- 
ries to the brain. If finally the usual shades and shadows 
are thrown in correctly—itself a mathematical process— 
the object will stand out from the flat surface on which it 
is drawn. 

The Oriental races—Chinese, Japanese, Hindus, Meso- 
potamians, and Egyptians had no conception of perspec- 
tive. Their drawings and paintings are absolutely flat. 
The Greeks and Romans had the idea, and made crude ef- 
ferts to embody it in their pictorial work, but having no 
knowledge of its laws, exercised their artistic tendencies 
mainly in the direction of sculpture and architecture. In 
the art of the Middle Ages these laws were recognized 
experimentally, but not having been worked out scien- 


190 Beacon Lights of Science 


tifically, many of the productions of the famous painters 
were absurdly distorted. Only those few in those days 
and even in the present time—who are natural geniuses, 
can make a picture approximating accuracy in its perspec- 
tive. To the architect and engineer a knowledge of its laws 
are an absolute necessity. 





BODE (1747-1826) 


ASTRONOMY 


JOHANN EHLERT BopE was a native of Hamburg, Ger- 
many; and became, even when a boy, an astronomical ob- 
server of note, with a telescope of his own make. In 1776 
he founded the ‘‘ Astronomische Jahrbuch,’’ and continued 
to be its editor and principal contributor for many years. 

His notable accomplishment was the publication, in 1801, 
of his ‘‘Uranographia,’’ consisting mainly of a catalogue 
of 17,240 of the stars. The magnitude and value of this 
production will be better understood when it is compared 
with all previously made siderial charts, the most compre- 
hensive of which included less than 6000 of the stars. 

Bode is popularly remembered, because of his prediction 
of the existence of a planetary body in the solar system 
then unknown, between the orbits of Mars and Jupiter. 
This was verified by the discovery in 1801, by Pacini, of 
the planetoid (or asteroid as it was then ealled) Ceres, 
the first of the group of small planets, of which now nearly 
500 have been detected. He was led to make the prediction 
because of a curious numerical relation in the position of 
the known planets with regard to the sun, which had been 
first noted by an astrologer named Titus, of Wittenberg, 
and in his day was thought to have considerable hidden sig- 
nificance. It is illustrated as follows: Write a row of nine 
fours, and under eight of them, beginning with the second, 
place three and its succeeding multiples by two. Then add 
the columns. 


The Eighteenth Century 191 


4 4 4 4 4 4 4 4 4 
3 612 24 48 96 192 £384 


4 Hee LO LO Sear Say LOO 196 388 
3.9 7.2 10 15.2 265 52 95.4 191.8 300.5 


If now the figure 10, in the third line, be taken as repre- 
senting the distance of the earth from the sun, then 4 
should represent the mean distance of Mercury, 7 that of 
Venus, 16 that of Mars, 28 of the planetoids, 52 of Jupiter, 
100 of Saturn, 196 of Uranus and 388 of Neptune. In the 
fourth line of figures is given the actual mean distance of 
the planets from the sun, relatively to that of the earth, 
which is again taken as 10. 

When Titus figured out this curious relationship, only 
the first four, and the sixth and seventh of the sun’s family, 
were known, and the correspondences were sufficiently 
striking to be suggestive. In Bode’s time Uranus had been 
located by Herschell (1781), and its computed distance 
from the center of the system corresponded so closely to the 
ratio shown by the table, as to excite renewed interest, par- 
ticularly as the irregularities subsequently found in its 
movements, seemed to point strongly to the existence of 
still another undiscovered planet. But when Neptune was 
found by Leverrier (1846), the symmetry of the system 
was severely shaken. Bode’s law, which had a great vogue 
in his day, was as follows: 

‘“‘The distances of the orbits of the planets from the 
orbit of the first one (Mercury), are, respectively, twice, 
four times, eight times and sixteen times that of the sec- 
ond planet (Venus).”’ 

It holds roughly for all except Neptune, and also for the 
moons of Saturn and Uranus, but not for those of Jupiter 
and Neptune. At the present time it has no standing as 
a law, but back of it there is probably some as yet unde- 
tected evolutionary sequence similar perhaps to that which 
chemists and physicists believe will ultimately be found 
behind the Periodic Table of the Elements, that was out- 
lined in 1868 by Mendeleef. 


192 Beacon Lights of Scvence 


WERNER (1748-1817) 


GEOLOGY 


ABRAHAM GOTTLOB WERNER was born at Wehrau in East 
Prussia. At the age of twenty he entered the famous min- 
ing school at Freiberg, and after graduating there with 
honor he supplemented his general educational equipment 
with a course at the University of Leipsic. His first pub- 
lished monograph on fossils won him the position of assis- 
tant instructor at the Freiberg mining school where, for 
forty years thereafter as major professor he taught his 
specialty so brilliantly as to gain for that institution a 
great reputation. It attracted students from all parts of 
the civilized world and, for a time, Werner was regarded 
as the supreme geological authority. 

But there was a fatal error at the foundation of his 
system of rock genesis and classification. It was based on 
their mineral composition, rather than upon their age, 
origin, mode of occurrence and relative stratigraphical 
position. He taught that all rocks were deposited by the 
ocean in the form of chemical precipitates. That granite 
—for instance—has been in process of formation in various 
places throughout all the geological periods; the basalt was 
a sedimentary deposit, as well as gneiss, schists and all 
lavas; that originally a universal ocean (the Noachic Flood) 
extended continuously around the globe, and out of which 
all the varieties of rocks then known were deposited by 
chemical action. To him, a voleano pouring out a stream 
of lava, was simply an elevation under which was a vast 
coal deposit which, by some means, at the time of eruption, 
had caught fire, and was melting and forcing out the water- 
formed rocks above it. And he defended these curious ideas 
with remarkable ability. 

The fact was that Werner, being a devout churchman, 
felt himself under obligations to employ his great powers 
and reputation in the construction and defense of a theory 
which could be squared with the orthodox concepts of Cre- 
ation, as told in the book of Genesis. And for a time he 


The Eighteenth Century 193 


succeeded brilliantly, for the influence of the Church in 
his day was supreme. Even the American geologist, Silli- 
man (1779-1864), being a deeply religious man, clung to 
his views to the end of his days. 

When Lyell’s great work ‘‘The Principles of Geology’’ 
appeared in 1830, Werner’s star began to set, and his the- 
ories are now almost forgotten. Nevertheless, he is entitled 
to be remembered as a man of high personal character and 
unusual ability as a teacher. In spite of the errors at the 
foundation of his theories he was the first geologist after 
Hutton to attempt to arrange systematically such facts 
about the past history of the globe as came to his knowl- 
edge in the rather limited region in which he made his 
observations. These he reported conscientiously, but erred 
in their interpretation. 


BERTHOLLET (1748-1822) 


CHEMISTRY 


CLAUDE Louts BERTHOLLET lived in Talliore in southeast- 
ern France, and was educated at the University of Turin, 
where he graduated in 1768 with the degree of doctor of 
medicine. He then went to Paris, and while practising his 
profession became deeply interested in chemistry. In 1789 
he was elected a member of the Academy of Sciences. 

At this period chemistry was just beginning to emerge 
from its alechemistic ancestry, and Berthollet ranged him- 
self at once with Lavoisier and others of the time, who were 
establishing the foundations of the new science. In 1785 
he announced his adherence to the antiphlogistic doctrine 
of Lavoisier, but differed with him—and correctly—as to 
the part played by oxygen in the composition of acids. In 
the same year he published a highly valuable paper on the 
bleaching properties of chlorine—then called dephlogisti- 
gated marine acid—and announced the true nature of 
ammonia aS a compound of nitrogen and hydrogen. In 
1794 he was appointed to the chair of chemistry at the 


194 Beacon Lights of Science 


Ecole Normale. After the Revolution, in 1815, he was ere- 
ated a peer by Louis XVIII. 

To Berthollet is due the very important addition to the 
idea of chemical affinity, that of chemical equilibrium, 
which means in effect, that a chemical reaction is not mathe- 
matically complete, until all the affinities of the elements 
taking part in it are satisfied. This is the fundamental 
principle of the science of stoicheiometry. His principal 
literary work entitled ‘‘Essai de Statique Chimique’’ ap- 
peared in Paris in 1803. 

Stoicheiometry is that branch of the science of chemistry 
which has to do with the calculation of the quantities of the 
elements involved in chemical reactions or processes. For 
example, a pure limestone consists of a combination in 
eertain definite proportions of the metallic element calcium, 
the non-metallic element carbon, and the elementary gas 
oxygen. If now to a given weight of such limestone, there 
be added a certain definite weight of sulphuric acid (a com- 
pound of the non-metallic element sulphur and the gaseous 
elements hydrogen and oxygen), a reaction will take place. 
The limestone as such and also the sulphuric acid will 
disappear. In their place will come into existence a totally 
new substanee with properties different with those pos- 
sessed by the others, which is popularly known as gypsum, 
and technically as calcium sulphate. And while this trans- 
formation is in progress there will be observed a lively 
ebullition or bubbling, indicative of the passing away of a 
gas. If now the solid mass resulting from the reaction be 
weighed, it will be found to be considerably lighter than 
the combined weight of the limestone and sulphuric acid 
employed. But if the gas that comes away during the 
operation be caught and weighed, and added to that of the 
sypsum produced, the combined weight will then be exactly 
equal to that of the limestone and sulphurie acid before 
they were placed together. 

In other words, matter, like force, is indestructible. It 
may change in place, in appearance and in its associations, 
but its quantity or mass as shown by its weight remains 
unaltered and unalterable, so long as it continues to exist 


The Eighteenth Century 195 


as matter. In any chemical reaction, when account has 
been taken of all the changes that have occurred, the com- 
bined weights of the new substances formed is invariably 
exactly equal to the combined weight of the materials that 
took part in their formation. This is the doctrine of the 
Conservation of Matter which, in Berthollet’s time, was 
just beginning to be grasped by the chemists of the day. 
If added proof of it were needed there is one which is 
unique, and not often called to mind. 

The sun, as is well known, is the theater of physical and 
chemical activies of the most violent nature. Its surface 
is a sea of incandescent matter at a temperature estimated 
at not less than 6000° centigrade. Underneath this is a 
layer of unknown thickness at even a higher temperature, 
from which enormous masses of gaseous matter are con- 
tinually breaking through the outer layer, and being pro- 
jected thousands of miles into surrounding space in the 
form of jets and spurts, which are called the protuberances. 
Yet the mass and weight of the sun does not vary, and 
has not within historic times. For an appreciable change 
in these respects would involve a corresponding one in 
the length of the terrestrial day, and no such change has 
occurred during the last eight to ten thousand years. 


JENNER (1749-1823) 


PHYSIOLOGY 


EpWARD JENNER, the son of a clergyman of the Angli- 
ean church, was born at Berkeley, in England. Exhibit- 
ing decided inclinations in his early youth to the study of 
medicine, he was apprenticed to a doctor in a nearby town, 
to learn the fundamentals of surgery and pharmacy. At 
the age of twenty-one he became a student at St. George’s 
hospital in London, and was a resident for two years at the 
home of John Hunter, who, with his brother William, were 
the most notable anatomists and physiologists of their day. 
Upon the recommendation of the former, young Jenner 
was appointed to arrange the floral and faunal collection 


196 Beacon Lights of Scrence 


brought to England by Capt. Cook, from his first voyage 
of discovery (1768-1771). The task was accomplished so 
well, that he was offered the position of naturalist to the 
second expedition. But having little inclination for a life 
of adventure, and loving country life, he (fortunately for 
the world) declined the position, and settled himself as a 
surgeon in his home town of Berkeley, devoting his spare 
time to ornithology, botany and mineralogy. He appears 
to have been among the first—if not the first—to connect 
the ailment known technically as angina pectoris, with the 
condition popularly called hardening of the arteries. In 
1792 he received the degree of M.D. from the St. Andrew’s 
University of Scotland. 

Twelve years previously, however, he communicated to 
the world his great discovery of the efficacy of vaccina- 
tion. Small pox was very prevalent—almost endemic—in 
Europe at the time, and already before his day, attention 
had been called a number of times to the partial immunity 
to the disease enjoyed by communities where cattle raising 
was an extensive industry, and particularly among those 
(herders and milkers) who were constantly in association 
with the animals. What is known as cowpox, is a disease 
peculiar to the cow, taking the form of bluish vesicles or 
blisters on the udder, which, when they break, discharge a 
limpid fluid. As early as 1763, it was known that milk- 
maids in Germany had no hesitancy in handling animals 
suffering with this disease. In 1774, a Gloucestershire 
farmer by the name of Benjamin Jesty, accidentally in- 
noculated himself while handling a cow infected with cow- 
pox, and finding that it had rendered him immune during 
a severe run of smallpox in his neighborhood, had the cour- 
age or hardihood to apply the remedy to his wife and two 
sons, with whom it proved equally efficacious. 

Jenner, living in the country, and having a large prac- 
tice among farmers and dairymen, became acquainted with 
these facts, and many others of a similar nature, and began 
an exhaustive investigation of the subject, which, in the 
end, created in his mind such confidence in his discovery, 
that in 1796, after vaccinating an 8-year-old boy with the 


The Eighteenth Century 197 


lymph obtained from a vesicle on the person of a milkmaid, 
who had been accidentally innoculated with cowpox in the 
course of her routine work, subsequently inoculated him 
with the smallpox virus, and found him to be completely 
immune. Here it should be stated that it had long been 
the practice in rural English communities (and perhaps 
elsewhere) to inoculate children with the smallpox virus, 
on the theory that they would come through the disease 
with less risk in infancy than later, and suffer less disfig- 
urement. In 1798 he published his great work on the sub- 
ject, which was entitled ‘‘An Inquiry into the Causes and 
Effects of Variolae Vacciniae Known by the Name of Cow- 
pox.’’ This book was translated into all the European 
languages, and attracted great attention. In 1803 Jenner 
founded the Royal Institution for the Extermination of 
Smallpox, and was its controlling director for many years. 

It is interesting to note that, when he first came to Lon- 
don to demonstrate the truth of his assertions, he was bit- 
terly assailed by city physicians and the clergy. Among 
the former, opposition died out quickly, but the latter as 
a class, with some notable exceptions, regarded vaccination 
as an act of gross impiety, just as the same class viewed 
life insurance when, a half century later, it became an es- 
tablished line of business. 

Jenner was a man of the highest principles and purest 
motives, and devoted himself so unreservedly to the gratui- 
tous exercise of his discovery, that his private practice was 
almost annihilated. The authorities of St. Thomas’s Hos- 
pital in London invited him to remove to that city, and 
guaranteed him a practice of £10,000 a year. When he 
declined this, because of his dislike of the city, and love of 
the country, his friends secured him a grant of that amount 
from Parliament, and later a second one of £2000. In 1811, 
the Empress of Russia, in token of her admiration and 
gratitude, sent him a diamond ring of great value and 
beauty. In fact, he was accorded full reward during life 
for his great discovery. He became the first honorary mem- 
ber of the Physical Society, was elected mayor of his native 
town, was given the freedom of the cities of Dublin and 


198 Beacon Lights of Sciencé 


Edinburgh, was made an honorary fellow of the Royal 
College of Physicians of Edinburgh, and was given the de- 
gree of M.D. by Oxford. In addition, when vaccination 
was formally adopted in the Royal Navy, its officers and 
surgeons presented him with a gold medal. His system 
was also adopted in the navies of France. Italy, Spain, 
Germany, Russia and the United States, and also in China 
and India. In the latter country, large sums of money 
were raised by popular subscription, and presented to him. 
His death resulted from an apoplectic stroke, in his 73rd 
year. Two statues, one in Gloucester, and one in London, 
were erected to his memory by popular subscription. 


LAPLACE (1749-1827) 


ASTRONOMY 


PIERRE SIMON DE LAPLACE, the son of a farmer, was 
born at Beaumont-en-Auge, in northern France. With the 
assistance of friends of his parents he secured a good 
primary education, and at the age of eighteen went to Paris. 
Being naturally a fine mathematician, he secured a position 
to teach that science at the Ecole Militaire, where he rap- 
idly made valuable friends, and acquired a high reputation 
in his specialty. In 1785 he became a full member of the 
Academy of Sciences, and in 1794 was appointed professor 
of mathematical analysis at the Ecole Normale. In 1817 
he was elected president of the Academy. 

Laplace is popularly known as the author of the ‘‘Nebular 
Hypothesis,’’? a theory of the origin and development of 
the solar system, which he enunciated in his ‘‘ Exposition 
du Systéme du Monde’’ (1796), and elaborated in his great 
work entitled ‘‘Mécanique Céleste,’’ which appeared in 
1799-1825. For nearly a century this notable treatise has 
been considered one of the world’s greatest contributions 
to the advance of knowledge, but during the last twenty 
years it has been subjected to much destructive criticism, 
and is not now regarded as a correct explanation of the way 
in which the sun and its family of planets and satellites 


The Eighteenth Century 199 


eame into existence. Nor has any other hypothesis been 
advanced that is not susceptible of more or less objection. 
In fact, the problem has not been solved to the satisfaction 
of astronomers, though the Planetismal theory is regarded 
as a nearer approach to a solution than the Nebular 
hypothesis. 

Aside from this, Laplace contributed several important 
and thoroughly accepted discoveries to science. In 1786 
he detected the dependence of the moon’s acceleration upon 
the secular changes in the eccentricity of the earth’s orbit, 
which is regarded as the keystone in the theory of the 
stability of the solar system. He also announced the laws 
of motion of the first three moons of Jupiter in the follow- 
ing terms: 

1. The sum of the mean movement of the first satellite, 
and of twice the third, equals three times that of the sec- 
ond. 

2. The sum of the mean longitude of the first satellite, 
and of double that of the second, diminished by three times 
that of the third, equals 180 degrees. 

Laplace’s theory, briefly outlined, was to the effect that 
the material of which the solar system is composed existed 
originally in the condition of an intensely hot and gaseous 
nebula of enormous extent and irregular shape, which grad- 
ually, under the action of gravitational forces, assumed a 
rotating and globular form. As it cooled it contracted, 
and from time to time successive rings of its substance were 
thrown off and left behind. These in turn consolidated into 
minor rotating nebulous masses and ultimately became the 
planets. Each of the latter, as the process proceeded, 
either themselves cast off rings to become satellites, as is 
the case with Neptune, Uranus, Jupiter, Mars and the 
Earth, or retained some of them as Saturn, with both satel- 
lites and rings, or consolidated into globes without satellites 
as was the case with Mercury and Venus. 


200 Beacon Lights of Science 


LEGENDRE (1752-1833) 


MATHEMATICS 


ApDRIEN Marte LEGENDRE was a resident in Paris, and 
educated there, becoming later the professor of mathe- 
maties in the Military and the Normal schools. In 1816 
he was appointed examiner for admission to the Heole Poly- 
technique. In 1824, in an election at the Academy of Sci- 
ences, because he refused to vote for the candidate of the 
government, he was deprived of his pension, and died in 
poverty. 

He was among the leaders in introducing the metric 
system and, in association with Prony, prepared the notable 
eentesimal and trigonometrical tables. He was the origi- 
nator of the method of least squares, and the discoverer of 
the law of quadratic reciprocity. His greatest work was a 
study on the ‘‘ Elliptical Functions.’’ His ‘‘Elements of 
Geometry’’ went through fifteen editions (the last being 
issued in 1881), and was a classic in the schools of the 
world for over a century. 

When the French government in 1790 began to discuss 
the establishment of a new and modern system of weights 
and measures, the first point to be decided was the selection 
of a unit which should be based upon a fundamental fact 
of nature; so that if its visible representative was lost or 
destroyed, its dimension could be recovered. Three of this 
kind were taken under consideration, namely, the length 
of a pendulum which, at sea level, and in a vacuum, would 
tick seconds; a quarter of the terrestrial equator; and a 
quarter of a terrestrial meridian. The last was chosen, and 
a committee organized to make the measurement of the are 
of the meridian extending from Dunkirk in France to 
Barcelona in Spain. When the task was accomplished, and 
the length of the terrestrial quadrant was computed from 
the measured length of this are, it was found to be 32,- 
808,922 English feet. One ten-millionth part of this, or 
39.37079 inches, was adopted as the unit of length, and 
given the name of the meter. On this as a fundamental, 


The Eighteenth Century 201 


all the other required units were based; namely, for land 
area, a square of 100 meters; for volume, a cubic meter; 
for weight, that of a cube of water at maximum density 
measuring one one-hundredth of a meter on all its edges, 
and called a gram; for capacity, a cube of water at maxi- 
mum density measuring one-tenth of a meter on all its 
edges, and called a liter. Appropriate names were then 
given to decimal multiples and divisions of these units. 

This system has since been made obligatory in most all 
the civilized nations except the United States and Great 
Britain, and in these two its use has been legalized, or 
made permissible, and is already almost universally em- 
ployed by the scientific fraternity, and undoubtedly will 
ultimately be adopted in the common transactions of life 
for, after more than a century of experience, its advantages 
have become manifest. 

However, it is now well known that the original meas- 
urement made of the are of the meridian between Dunkirk 
and Barcelona was erroneous, and also that changes are 
constantly in progress in the shape and size of the globe, 
which makes it impossible to derive an unalterable unit 
of length from that source. For this reason, at the Paris 
Exposition of 1867, an international committee was ap- 
pointed to arrange for the construction of a number of 
standard meters, to be distributed among the principal na- 
tions. This committee assembled in Paris in 1872, and 
settled upon an alloy of the metals platinum and iridium 
as the material to be employed in their manufacture, the 
meter to be in the form of a bar, and the gram (or kilo- 
eram) in that of a cylinder. 

In recent years it has been suggested that a more per- 
fect natural unit could be derived from the number of 
undulations per unit length characteristic of the light given 
by certain incandescent metals under given conditions, and 
one that could more easily be recovered or reproduced. 
But it is not at all likely that any such change will be made. 


202 Beacon Lights of Scrence 


RUMFORD (1753-1814) 


PHYSICS 


BENJAMIN THOMPSON (Count Rumford), a native of the 
town of Woburn, Massachusetts, with a most engaging per- 
sonality, and strong inclination towards such sciences as ex- 
isted in his day, was compelled to go to work as a clerk at 
the age of thirteen. But three years thereafter he married 
a wealthy widow of Concord, New Hampshire, which not 
only relieved him from all financial worries, but gave him a 
social standing in the community, and resulted in his ap- 
pointment by the governor of the colony to the honorable 
position of major of the militia. Being a pronounced royal- 
ist as well as a man of courage and determination, he and 
his wife—who shared his political views—found continued 
residence in Woburn distasteful, by reason of the decided 
inclination of a majority of the community to separation 
from the mother country. In consequence of this he moved 
to Boston, and when that city was evacuated by the Brit- 
ish in 1776, he went to London, bearing important dis- 
patches to the government. There, having made a most 
favorable impression, he was given a post in the Colonial 
Office, and later was advanced to the position of Under 
Secretary of State. In 1779, in recognition of scientific 
studies and experiments, he was elected a Fellow of the 
Royal Society. 

Shortly before the close of the American Revolutionary 
War he returned to America, in the capacity of an officer 
of the English army, but upon the surrender of Cornwallis 
in 1781 he returned to Europe, took service in the army 
of Bavaria, and settled in Munich in 1784. Being a man 
of fine presence, attractive disposition, and excellent char- 
acter, he rose rapidly in the profession of arms, attaining 
in turn the rank of major general, military councilor of 
State, lieutenant general, and Minister of War. Finally, 
in recognition of both his scientific and military eminence, 
he was created a Count of the Holy Roman Empire, choos- 
ing Rumford for his title, as that had been the name of 


The Eighteenth Century 203 


the town of Concord, New Hampshire, previous to the year 
1765, where he considered his good fortune to have begun. 
In 1799 he retired from military service in Bavaria, and 
went to London, where he took a prominent part in the 
founding and establishment of the Royal Institution. Later 
he moved to Paris where, his first wife having died, he mar- 
ried the widow of Lavoisier, the famous French chemist, 
and remained in that country until his death in 1814. 

Aside from having led a most picturesque life, his title 
to recognition as one of the great discoverers arises mainly 
from his investigations and experiments on the subject of 
heat. Up to the year 1800, heat was regarded as a sort 
of fixed matter, which was inherent in all combustible sub- 
stances. To it was given by Professor Stahl of the Uni- 
versity of Halle (1660-1734), the specific name of ‘‘ phlog- 
iston.’’ Ag an illustration of the concept as it existed in 
the minds of the pseudo-chemists of that day, the phenom- 
ena which occur in the reduction of an ore of iron (say 
hematite) to the metallic state, may be cited. To bring 
about the change, the ore is mixed intimately with charcoal, 
the latter induced to burn, and the combustion intensified 
with the bellows. Under such treatment both the charcoal 
and the phiogiston combined with the hematite disappear, 
leaving the pure metal behind, the inference being that 
there had been brought about a destruction of the com- 
pound of the phlogiston with the iron. To account for the 
fact that the resulting metal weighed somewhat less than 
the ore from which it came, it was taught that phlogiston 
was a substance of great tenuity, lighter even than air. 
Finally, when it was pointed out that the specific gravity 
of the metal was higher than that of hematite, it became 
necessary to advance the conception of phlogiston to that 
of a substance having no weight at all. 

This pre-chemical theory of the nature of heat, was 
further elaborated by giving another name (caloric) to the 
phenomenon, and picturing it as a fluid of an elastic and 
self-repellent nature, which permeated all matter. 

Although various scientists before his day (Descartes, 
Boyle, Francis Bacon, Hooke and Newton), either in so 


204. Beacon Lights of Science 


many words, or inferentially, had expressed the opinion 
that the phenomenon must be due in some way to motion in 
or of the substance heated, they had been unable to furnish 
any proofs of such a theory. It is to the credit of Rum- 
ford that he announced the definite conclusion that heat 
was merely a form of that force known as motion, and to 
prove his contention by boring a hole in a bar of soft. iron, 
by means of a tool of steel, and inviting consideration of 
the heat produced by friction in both, without altering the 
appearance, the weight or nature of either. The demon- 
stration was characteristic of the man, and before it the 
vagaries of the phlogiston and ealoric hypotheses faded 
away like mist under the rays of the sun. 


PROUST (1754-1826) 


CHEMISTRY 


JOSEPH Louis Proust was brought up in Angers, France, 
received his primary education there, and his higher ele- 
ments in Paris, where he became chief apothecary to the 
Salpétriére, a hospital for the helpless and insane. 

He placed on a firm basis the chemical law of definite 
and multiple proportions, and discovered glucose in 1799. 
He greatly advanced the technic and knowledge of quan- 
titative anlysis. 

Glucose is one of the most interesting of natural organic’ 
products, and since it has been learned how to produce 
it synthetically has become an important article of com- 
merce. It is one of those substances called carbohydrates 
or hydrocarbons indifferently, its molecule consisting of 6 
atoms of carbon, 12 of hydrogen and 6 of oxygen. It occurs 
in most of the common fruits—grapes, cherries, bananas, 
apples, pears, plums, ete. It may often be found in the 
crystalline state in figs, raisins and dates, and in candied 
honey, and is the cause of the sweet flavor in all of them. 
It originally was called grape sugar. Yet it is not sugar, 
for the molecule of the latter contains 12 atoms of carbon, 
22 of hydrogen and 11 of oxygen. It may be regarded as 


The Eighteenth Century 205 


a halfway step on the part of nature towards the produc- 
tion of the true article. 

Curiously enough, while the sugar produced from the 
cane and the beet is, so far as it goes, a perfect animal 
food—being completely assimilated—yet glucose is in no 
respect a food, and though very extensively consumed in 
the forms of candy and syrups, where it is an adulterant, 
passes through the digestive system unassimilated. In 
fact, if any of it is retained, it becomes the source or cause 
of several well-known diseases, one of which—diabetes—is 
often fatal. 

On the other hand, glucose is a natural food for the 
vegetable world, which consumes it avidly, and transforms 
it ito other members of the sugar family (including the 
genuine article), or into starch. Its relative sweetening 
power is estimated at from one-half to three-fifths of that 
of the true sugar. 

In 1890 the chemist Fischer succeeded in making glu- 
cose. The raw material employed is any form of starch, 
in Europe mainly from the potato, in America from corn. 
The transformation into glucose is effected by the aid of a 
small quantity of either nitric, hydrochloric or sulphuric 
acid, in steam heated and closed converters, under pres- 
sures ranging from 30 to 45 pounds, and in the presence 
of a considerable quantity of water; and is completed in 
a half hour or less. The product is a white syrupy sub- 
stance, which is loaded into barrels for shipment. The 
industry is now a very large one. On account of its prop- 
erty of moderate sweetness it is very extensively used in 
the manufacture of fruit jellies, candies, and practically 
all the many varieties of table syrup that are on the market. 


PRONY (1755-1839 ) 


MATHEMATICS 


GaAsPAaRD CLAIR FrRANcoIS Marie RicHE PRoNyY was born 
at Chamelot in Franee, was educated at the Ecole des Ponts 
et Chaussées as an engineer, and had charge of the restora- 


206 Beacon Lights of Science 


tion of the harbor of Dunkirk, afterwards becoming pro- 
fessor of mathematics at the Ecole Polytechnique at Paris. 
Later he was appointed chief of the Ecole des Ponts, and 
continued as a government official in one capacity and 
another during the remainder of his career. 

His notable scientific accomplishment was the completion 
of a table of Logarithms based on the decimal system, and 
extended to the 25th decimal digit—a wonderful perform- 
ance. 

Logarithms are tables of numbers so constructed, that 
by their use various long arithmetical calculations may be 
shortened. Thus, multiplication can be performed by addi- 
tion; division by subtraction; involution (powers) by a 
single multiplication; and evolution (roots) by a single 
division. John Napier, a Scotchman, is regarded as the 
inventor of the idea, having published his work on the sub- 
ject in 1614. 

Mathematically defined, the logarithm of a number is 
‘‘the exponent of the base number which produces that 
number.’’ For example: If 3 is selected as a base, and 
raised to its 5th power (243), it is then said that on a 
base of 3 the number 5 is the logarithm of 248. Or, for 
further elucidation, let 4 be taken as the base. Then 4 
raised to its 8th power would produce 65,536, in which case 
the figure 8 would be the logarithm of 65,536. Thus it 
appears that by varying the base any desired number of 
logarithmic systems may be constructed, in each of which 
the logarithm of any given number will be different from 
that in all the other systems. As a matter of fact several 
such systems besides that of Napier were worked out with 
vast labor, among which may be mentioned those of Burgi, 
Speidell and Briggs. The last employed the figure 10 as a 
natural base, and calculated the logarithms of numbers 
from 1 to 20,000, and from 90,000 to 100,000 on that base, 
extending his calculations for each number to fourteen 
decimals. Vlacq and Gellibrand in collaboration worked 
out those omitted from his tables (20,001 to 89,999). The 
work of Prony consisted in extending the figures of these 
pioneers to the 25th decimal. By referring to the chapter 


The Eighteenth Century 207 


devoted to Napier, an example will be found of the use of 
the system. The base of 10 is now universally employed. 


CHLADNI (1756-1827) 


PHYSICS 


ERNEST FLORENS FRIEDRICH CHLADNI was a native of 
Wittenberg, Germany, and studied law there, and at the 
University of Leipsic, but abandoned the profession in order 
to devote himself to the physical sciences. Being a musi- 
cian of ability he was naturally attracted particularly to 
the phenomena of sound, in which his investigations led 
him to the discovery of the laws governing the vibration 
of strings, rods and surfaces, under the influences of fric- 
tion, percussion and other varieties of strain. He deter- 
mined the velocity of sound waves in the air, and in other 
gases, and devised a number of apparatuses for exhibiting 
the visible effects of oscillations. Among these, perhaps 
the most notable was that which displayed the symmetrical 
formations assumed by grains of sand under the influence 
of rhythmical vibration, producing what were known as 
the ‘‘Chladni Figures.’’ A thin plate of metal, glass or 
wood, of any symmetrical form—as a disk, square or poly- 
gon—was clamped at its central point horizontally to any 
firm support, and evenly sprinkled with fine and clean sand. 
When the edge was rubbed with a violin bow or set in 
vibratory motion by percussion, the sand disposed itself 
around the clamped center in symmetrical forms and fig- 
ures, that exihibit the lines of strain and elasticity where- 
ever the plate is free to respond to such. 

Sound, like light, is (in one sense) a mental phenomenon. 
Neither exist for the deaf and the blind. Yet if there were 
no such things as ears and eyes in the world, the vibrations 
which are capable of affecting both would still be in exist- 
ence. The assumed ether of space that transports light 
waves with such amazing speed will not carry those of 
scund. Nor will the dense matter which ordinarily conveys 
sound waves convey those of light, unless endowed with 


208 Beacon Laghts of Science 


the character called transparency or translucency. Yet if 
one end of a metal bar be placed in strong sunlight and 
the rest of it carefully shielded, in due time the light, trans- 
formed into heat, will become apparent to the sense of 
touch at the protected end. On the other hand, the denser 
the material body—within certain limits of elasticity—the 
better conductor it becomes of the waves of sound, and 
without transformation into any other form of energy. 
The notable experiment made by Von Guericke showed that 
matter of some kind must be present if sound is to be 
transmitted. Right here, however, we are confronted with 
the recent discovery—apparently authentic—that matter 
of all known kinds is nothing more than a newly recognized 
manifestation of energy. 

Water, being almost incompressible, will carry sound 
vibrations at the rate of about 4700 feet per second. This 
property has recently been employed in ascertaining ocean 
depths. The apparatus is attached to the under side of the 
ship, and is capable of emitting a sharp sound. The vibra- 
tions in the water so initiated are carried to the ocean floor 
beneath, which at once reflects them back. A membrane is 
provided to receive these returning waves, and to announce 
their arrival. The time required for the round trip is 
simultaneously recorded. Making such proper allowance 
for the slow but steady dissipation of the undulations as 
has been determined by experience, the results have been 
shown to be very accurate. 

In the phenomenon of sound the matter of loudness is 
determined by the amplitude of the waves, that is, the dis- 
tance from crest to crest. In the matter of pitch, that is, 
whether the note is a high or low one on the scale, the de- 
termining feature is the number of vibrations which reach 
the ear per second of time, A noise is an abrupt, irregular 
and very complex combination of vibrations. A musical 
note is a simple and regular train of them. A harmonious 
chord is a combination of the latter on strictly mathemati- 
eal principles, while a discord is the exact opposite. 

The acoustic properties of an auditorium are entirely 
independent of the location of the musical instrument or 


The Evghteenth Century 209 


the speaker, or of the position of the hearer, unless the 
ceiling is specially constructed for sound transmission; but 
are dependent upon its size and shape, and the material of 
the walls, floor, ceiling and furniture. Thus, in an empty 
hall finished throughout in hard wood and without uphol- 
stered seats, the reverberations or echoes will be at a maxi- 
mum, and will almost destroy the effect of any music or 
speech delivered in it. But if it be carpeted, if the walls 
are of plaster on wood or wire lath—the last preferable—if 
filled with a large audience and with hanging, house plants, 
etc., its acoustic properties will be vastly improved. 
Finally, if the walls and ceiling are covered with tapestry, 
or some form of rough finish plaster with hair or other 
fiber projecting slightly from its surface, reverberation and 
echo will be reduced to a minimum. And if in such a, hall 
the audience is entirely of women, a still further marked 
improvement will be noticeable, due to the greater degree 
of fluffiness in their attire as compared with that of men. 


WOLLASTON (1766-1828) 


CHEMISTRY 


WituiAM Hype Wo.LAston was of English birth and 
ancestry, and after completing his education in medicine at 
Cambridge began practice in London. But meeting with a 
severe business disappointment he abandoned the profes- 
sion and turned his attention to science, where he attained 
a high reputation in chemistry, physics and optics. He was 
the first to recognize and partially investigate the dark 
absorption lines in the solar spectrum, but for some un- 
known reason did not follow up the matter, which was for- 
gotten until they were re-discovered and explained by 
Fraunhofer. His researches in optics yielded the inven- 
tion of the camera lucida and the goniometer, the first of 
which is quite indispensable in microscopic work, and the 
latter in the measurement of the angles of crystals. 

But in the annals of chemistry his name is associated 
more than that of any other scientist with that most inter- 


210 Beacon Lights of Science 


esting group of elements known as the platinum metals. 
These, in the order of their discovery are platinum (1750), 
palladium and rhodium (1803), iridium and osmium (1804) 
and ruthenium (1845). Of these Wollaston was the 
discoverer of only palladium and rhodium. But his isolation 
of them directed the attention of chemists at once to the 
group, which is one of very unusual properties. All but plat- 
inum are extremely rare in nature, and is itself found only 
in a few localities in amount sufficient to warrant commer- 
cial operations for its recovery. All are white in color except 
osmium, which has a distinct blue-white tint. They are 
almost universally found in the pure or native condition, 
associated more or less with each other and also with gold. 
There is much similarity in their properties, such as great 
hardness, high specific gravity, strong resistance to heat 
and to the attacks of air, moisture and the most powerful 
acids. Osmium has a specific gravity of 22.5, and is there- 
tore, for equal volumes, the heaviest substance known, 
which means the most dense. Iridium requires a tempera- 
ture of 2500° Centigrade (4704° Fahrenheit) before it will 
melt. So hard is this metal and so unalterable, that it is 
employed for the tips of gold pens. The high melting 
point of platinum (1800° to 2000° Centigrade), combined 
with its malleability, ductility and resistance to the attack 
of chemical reagents, makes it indispensable as a material 
for crucibles in the laboratory, and for conductors in elec- 
trical installations. An alloy of ninety parts of platinum 
to ten parts of iridium constitutes a metal so completely re- 
sistant to change, and so beautiful in appearance, that it 
was selected as the most suitable material for the standard 
bars and cylinders that were made in Paris and distributed 
among scientific societies of the civilized nations as the 
units of measure (the meter), and of weight (the kilo- 
gram), of the metric system. The outstanding property of 
palladium is its exceedingly fine molecular structure, sur- 
face hardness and brillianey, which permits lines to be 
drawn upon it so close together and yet so permanent and 
true, aS to make its use most desirable for the manufacture 
of fine scales for scientific instruments. In the form of a 


O1c 26nd bBu19s0q 
em : set : sauas fo Kwapvrp ouo1uvN © 





a | ee NOC 
WaT RE ICIOUNRE 


SE Re gt gO ge 


Tae 
F- ‘Ten ; 
- » : ~ ¥ - 
: ® 
dy 


é en 
7 z 
- = ¢ q . a 
a a ® = @ 
e. 
. ~ = 
=} 
~ 46 —4 
; 
P 
. 
a 
i 
' ' 


| Iie LiBHARY - 
OF THE. 
UNIVERSITY OF SLUMS 


s 
! . 
2 
i 
. os ¥ 
™~ 
! 
4 
: ‘ 
. bal 
on 
va 
Fe * ar 





The Exghteenth Century 211 


delicate wire it finds employment in dentistry on account 
of its hardness and resistance to corrosive action of all 
kinds. For ruthenium no uses have as yet been found in 
the arts. A small quantity of rhodium when added to steel 
in the melt, makes an alloy so hard, so elastic and so unal- 
terable, as to be exceedingly desirable for the manufacture 
of certain surgical instruments, where a keen cutting edge 
must be maintained. Altogether these six rare metals seem 
to be set apart in their properties by nature for the especial 
service of science. An interesting feature in connection 
with ruthenium was its discovery by Osann in 1828, fol- 
lowed very shortly by a withdrawal of the claim, and its 
rediscovery in the same material on which Osann was work- 
ing, by Claus in 1845. 

Nearly all of the platinum heretofore produced has come 
from the placer deposits in the Ural mountains of Russia, 
but of recent years a steadily increasing amount has been 
produced from similar deposits in the Republic of Colom- 
bia. Tasmania is at present the source of almost all the 
iridium and osmium that is coming into the market, and 
Central Africa of the palladium. 


DALTON (1766-1844) 


CHEMISTRY 


JOHN Daron, the son of a poor weaver, lived in Eagles- 
field, England, and received his early education in his 
native town. At the age of sixteen he was sent to a board- 
ing school at Kendal, a neighboring village. Here he ex- 
hibted such marked ability in mathematics and physics, 
that he was soon teaching those subjects to younger schol- 
ars, and at the same time increasing his own stock of 
knowledge by private study. This brought its appropriate 
reward in 1793, in the form of an offer of the chair of 
mathematics and natural philosophy in the New College 
just established in Manchester. He accepted this, and con- 
tinued a resident of that city for the balance of his life. 

He now had the opportunity, in the laboratory of this 


212 Beacon Lnghts of Science 


institution, to specialize in physical chemistry; and recall- 
ing the theories which had been expressed more than a 
century previously by Boyle (1627-1691), on the subject 
of the elements, and the conclusions reached by Lavoisier, 
Davy, and others of his own time, he announced in 1804, 
as a theory which he had demonstrated experimentally, his 
law of Multiple Proportions, which is expressed concisely 
as follows: 

‘“When a given quantity of an element (as A) unites 
with several different quantities of another element (as 
B)’’ (on different occasions of course) ‘‘these several dif- 
ferent quantities of B will bear a simple mathematical ratio 
to each other.’’ 

Perhaps the most familiar example of the law is pre- 
sented in the case of the several ores of iron, as follows: 


Ferrous oxide, black: ini colors... sss eeee ne ee oo FeO 
Ferrie:oxide, red Colors soa. sue cy eae ee Fe.03. 
Magnetic oxide, black in color.................. Fe;O, 


On the firm basis of this principle, Dalton was the first 
to establish a rational connection between the defective 
atomic hypotheses in existence at the time, and the real 
facts of chemical composition upon which the universally 
accepted Atomic Theory of the present day is securely 
founded, an achievement which establishes him as the real 
parent of that modern science. Between 1808 and 1810 he 
_ published his ‘‘New System of Chemistry,’’ in which his 
atomic theory was elaborated on mathematical principles, 
and in such a way that an entirely new light was thrown on 
the composition of matter, and the relations of the elements 
to each other. And although the Daltonian system of 
‘‘combining equivalents’’ has since been superseded by the 
system of atomic weights, the discovery of the principles at 
the foundation of both are due almost wholly to his investi- 
gations. 

In 1817 he was elected president of the Literary and 
Philosophical Society of Manchester. Later he attained 
membership in the Royal Society of London, and the Paris 
Academy. In 1833 he received a government pension of 


The Eighteenth Century 213 


£150, which was afterwards raised to £300; and at the 
same time a statue to his honor was unveiled at the entrance 
to the Royal Institution in Manchester, at the cost of its 
citizens. He also received the degree of D.C.L. from Ox- 
ford, and that of LL.D. from the University of Edinburgh. 

In person he was a man of simple, grave and reserved 
manners, yet kindly; and distinguished for integrity of 
character and modesty of demeanor. He wrote and pub- 
lished, in the scientific periodicals of the day, a number of 
valuable papers on gases (including steam), and on mete- 
orological subjects, all of which were notable contributions 
to the advance of knowledge. Considering the limited and 
even hard conditions of his youth, few have made a record 
of accomplishments so notable, or that produced such re- 
sults for those who since have followed in the path he 
blazed. At a blow, he changed the speculations of alchemy 
into the science of chemistry. 


CUVIER (1769-1832) 


ANATOMY 


GEORGES LEOPOLD CHRETIEN F'REDERIC DAGOBERT CUVIER 
was a native of Montébeliard in eastern France. He was 
brought up very strictly in the Calvinistic faith, and at the 
age of fourteen was sent to the academy at Stuttgart, with 
the expectation that, after passing through its course, he 
was to study for the ministry. But he displayed so little 
inclination towards that profession, and so much enthusi- 
asm and ability in natural history, that he was wisely al- 
lowed to have his way. In 1788 he became a tutor in the 
family of a Protestant nobleman living near Caen, on the 
coast of Normandy, where unusual opportunities existed 
for the study of marine life and fossils. In 1795 he went 
to Paris, and became assistant to the professor of com- 
parative anatomy at the Museum of Natural History, and 
at once took a high position in scientific circles. In the 
following year he was chosen professor of natural history 
at the central school of the Panthéon, and in 1800 elected 
to the same position in the College of France. In 1802 


214 Beacon Laghts of Science 


he took charge of the Jardin des Plantes, and began his 
career as a political administrator, when he was appointed 
an Inspector of Education under the Consulate. When 
Napoleon became Emperor, he was appointed a member 
of the Council of the Imperial University, a position which 
compelled him to travel extensively in Italy, Holland and 
Germany. In 1814 he became a Counselor of State, and 
retained his position after the fall of Napoleon. In 1818 
he was elected a member of the Academy of Sciences, and 
in the following year became president of the Committee 
of the Interior, and Chancellor of the University of Paris. 

In 1822 he was appointed Grand Master of the Faculties 
of Protestant Theology. In 1826 he became a grand officer 
of the Legion of Honor, and in 1832 the King (Louis 
Philippe), made him a peer of the realm, and was con- 
sidering him for the post of Minister of the Interior when 
he was seized with his final illness. 

Few careers have been so uniformly brilliant and suc- 
cessful as that of Cuvier. And when it is remembered that 
he continued from first to last an openly professed Protes- 
tant of the most pronounced Calvinistic type, in a land 
overwhelmingly Catholic in its religion, it is impossible to 
avoid the conclusion, either that by then France had 
learned much of the lesson of tolerance, or that Cuvier was 
a man of very lofty character, and great personal charm. 
No doubt both are warranted. 

His standing as a discoverer in the domain of science, 
rests mainly on the investigations detailed in his book en- 
titled ‘‘Tablea Elémentaire de Il’histoire Naturelle des- 
Animaux,’’ which appeared in 1798. In it, he gave the 
outline of his system of classification of animal life. It 
was at once accepted throughout the intelligent world, as 
a revolutionary production. And when, in the years be- 
tween 1800 and 1803, the five volumes of his ‘‘Lecons 
d’Anatomie’’ came one by one from the press, he was uni- 
versally recognized as the founder of the science of Com- 
parative Anatomy. His third great work ‘‘Le Régne Ani- 
mal,’’ published in 1816, remained the standard on its sub- 
ject for many years. 


The Exghteenth Century 215 


Previous to his time, the classification of animal life by 
the Swedish naturalist, Linnaeus, had been accepted every- 
where, being based upon the belief that each particular 
Species was immutably established at the time of the cre- 
ation of the world, as related in the Bible, and his system 
was therefore wholly a descriptive one, founded merely 
upon external appearances and habits. In his day little 
was known, and less understood, of the facts of anatomy. 

Cuvier, however, was an anatomist, and his system of 
classification was the result of studies of the internal parts 
(the skeleton), as well as the external. Curiously enough, 
though his observations must have indicated the probability 
of the mutability of species, and the slow but steady devel- 
opment from simple forms of life to others more complex, 
yet his religious standards and convictions were so strong in 
consequence of his early training, that he was unable to 
see—or perhaps to admit—any possibility of development, 
or evolution as we would now eall it; and so, when Lamarck 
the naturalist, boldly intimated a belief in the mutability 
of species, and advanced the theory that all life was de- 
rived from a primitive common stock, with man at the 
head of the order of Primates, Cuvier at once affirmed his 
belief in the Creation as described in the book of Genesis, 
and his great reputation caused the views of Lamarck to 
sink into obscurity and be forgotten, until revived by the 
genius of Darwin fifty-odd years later. 


HUMBOLDT (1769-1859) 


NATURAL HISTORY 


ALEXANDER VON HUMBOLDT was born in Berlin of 
wealthy and titled parents, received his education in fun- 
damentals from private tutors, and in the higher branches 
at the Universities of Frankfort, Berlin and Gottingen. 
Becoming strongly interested in geology he took a course 
at the mining school at Freiberg in 1791, at the time when 
Werner was at the height of his reputation there as profes- 
sor of that science and of mining engineering. In 1792 


216 Beacon Inghts of Scrence 


he was appointed government superintendent of mines for 
the principalities of Bayreuth and Anspach in Bavaria, 
which he held for five years. By that time his natural 
inclination towards travel and exploratory work led him 
to resign, and prepare for the great journey in Spanish 
America, his accounts of which have had most to do with 
making his name famous. Going first to Paris, where he 
made the acquaintance and secured the companionship of 
the botanist, Bonpland, and from there to Spain to obtain 
letters to the Viceroys of its colonies, they sailed from 
Corunna in the summer of 1799 for Venezuela, and landed 
at the Venezuelan port of Cumana. From there began their 
remarkable journey through the New World, which ex- 
tended up the valley of the Orinoco to its southern head, 
through Eeuador, Peru and northern Bolivia, regions 
whose geography and physiography were then almost 
wholly unknown. From Peru they took ship to Mexico, 
landing at Acapulco in 1803, and after traveling for a year 
in that country, and collecting valuable information of its 
mineral resources, returned to Europe by way of Cuba, 
landing at Bordeaux in the autumn of 1804. 

In 1829, having in the meantime worked up and pub- 
lished the notes of his American journey, he traveled 
through Russia and into Siberia as far eastward as the 
Yenesei valley, under the patronage of the government. 
The notes of this journey were published in the years be- 
tween 1830 and 1848. The remainder of his long and 
active life was passed in Germany, and devoted mainly to 
the preparation and publication of his great work ‘‘Cos- 
mos,’’ which appeared in four volumes in the years between 
1845 and 1858. These were translated as fast as they came 
from the press, into all the great modern languages, and 
created a profound impression. In it he attempted a 
physical description of the Universe, setting forth all the 
knowledge that had been acquired to his date in all the 
departments of science. Naturally, since then, some of his 
statements and conclusions have been found to be erroneous. 

The life and career of Humboldt was, in many respects, 
a parallel to that of the famous Italian traveler of the 


The Exghteenth Century 217 


Middle Ages, Mareo Polo (1254-1324). The latter had 
for his object to bring to the European world of his day 
a knowledge of that Asiatic world whose existence had long 
been known, but of which almost nothing had been learned 
except that it was densely populated, and supposed to con. 
tain enormous resources of wealth, of which at the time 
Europe was in dire need. Humboldt’s journeyings on the 
contrary were, in both cases, to regions sparsely populated, 
and then mainly by savages, or very primitive people, yet 
also believed to be teeming with raw wealth. There was 
also this difference; that while each explorer was well 
equipped with the best education of his day, that of the 
Italian was of the old philosophical and theological order, 
while the German possessed in addition the new intellec- 
tual tool of science. In consequence, the accounts given to 
the world by Humboldt were of exceptional value as well 
as interest; for while he contributed little to the stock of 
pure science, his additions to geography, physiography, 
geology, ethnology and meteorology came at a time in the 
history of civilization when just that kind of information 
was needed, to enable Europe to put into practice in com- 
mercial ways the forces of nature which by that time had 
been brought under control by the physicist, the engineer 
and the chemist. Moreover, the new information was eare- 
fully gathered, accurately reported, and to a very large 
extent dependable. As a specific instance of these the dis- 
covery of the common source of the Orinoco and Amazon 
rivers may be mentioned. 


OERSTED (1777-1851) 


PHYSICS 


Hans CHRISTIAN OERSTED was a native of Rudkjobing 
in Denmark, and studied at the University of Copenhagen, 
where he received his degree of Ph.D. For a time he earned 
his living by lecturing on chemistry and natural philos- 
ophy. He then traveled for several years in Holland, Ger- 
many and France, after which, in 1806, he received the 
appointment of professor of physics at his alma mater. 


218 Beacon Lights of Science 


Oersted’s claim for honorable distinction in science is 
based upon his discovery in 1819 that a magnetic needle, 
if suspended by a silk thread, so that it rests in a horizontal 
plane, and if then surrounded with a coil of wire through 
which an electric current is passed, will be deflected from 
its normal north and south position. This was the first 
recorded experiment of note in electromagnetism, and at 
once made possible the galvanometer, the electromagnet and 
other devices of this kind; as well as establishing such an 
intimate relationship between the phenomena of electricity 
and magnetism, as led in a short time to the demonstration 
of the identity of the two forces. The details of the experi- 
ment were published by Oersted in a pamphlet entitled 
‘‘Hxperimenta Cirea Effectum Conflictus Electrici in Acum 
Maeneticam.’’ In recognition of the value and importance 
of this discovery, Oersted received the Copley medal from 
the Royal Society of London, and the mathematical prize 
from the Paris Institute. 

He was an attractive lecturer and writer on scientific sub- 
jects, and devoted much of his time to the production and 
publication of scientific monographs written in non-techni- 
eal language, and in courses of popular scientific addresses, 
which were eagerly attended and highly appreciated by the 
masses of the people. 

The galvanometer is an instrument for detecting and 
measuring the presence and strength of an electric current 
passing along a wire. It consists of a magnet suspended 
horizontally at its center, in such a manner that it is free 
to move sideways in either direction. Around this, in a 
vertical plane, a coil of wire connected with a battery is 
wound. When the current is turned into it a magnetic 
field is created in the space in which the needle hangs. 
_ Immediately the latter begins to swing out of its true north 
and south direction, to an extent proportional to the 
strength of the current in the coil, and to its own length 
and strength as the result of the action upon it by the mag- 
netic force of the earth. In operation, if the current in 
the coil is flowing from south to north, the north pole of 
the magnet will be deflected to the west; and to the east if 


The Exghteenth Century 219 


it is flowing in the opposite direction; and the amount of 
deflection resulting is a measure of the relative strength 
of the two forces in action. 

Several improvements on this primitive device have been 
made, one of which—by Nobili—employs two magnets sus- 
pended one above the other a short distance apart, and with 
their poles reversed, so that they neutralize each other, and 
will remain in whatever direction they are placed. This 
is called the astatic galvanometer. If now the coil con- 
veying the electric current—suspended horizontally in this 
case—is so placed that the lower needle is within the plane 
of the coil, and the upper needle is above it, the deflection 
resulting is greater. Thus, in a general way, the astatic 
arrangement is more delicate, and will register the strength 
of a weaker current. A still more delicate device origi- 
nated with Sir William Thomson, and is known as the re- 
flecting galvanometer. In the D’Arsonval device the mag- 
nets are fixed, and the coil is suspended so as to be capable 
of moving. This form is perhaps more extensively used at 
present than any of the many other varieties that have 
been invented, but in all of them the principles involved 
are identical. 


BROWN (1773-1858) 


BOTANY 


Rosert Brown was born at Montrose, Scotland, and edu- 
eated at the University of Aberdeen. After taking a sup- 
plementary course in medicine at Edinburgh he became 
attached, as assistant surgeon, to a Scottish regiment that 
was stationed in Ireland. He remained with them for five 
years, devoting all his spare time to the study of the flora 
of that island, which is largely composed of grasses, sedges, 
rushes and ferns, but very diversified within those limits. 
In 1800 he resigned his commission, and accepted the posi- 
tion of naturalist on an expedition to investigate the botan- 
ical conditions of the coasts of the Australian continent. 
When he returned he brought a collection of nearly 4000 


220 Beacon Laghts of Science 


specimens, of which more than half were entirely new to 
scienee. Shortly thereafter he was appointed librarian of 
the Linnaen Society in London, and settled down to the 
occupation of writing botanical monographs which were 
published in its ‘‘Transactions,’’ and of geological essays 
for the Wernerian Society at Edinburgh, of which he was 
a member. But the influence and classification systems of 
both these worthy men were, at the time, fast undergoing 
eclipse under the newer and more scientific systems of 
De Jussieu and Lyell, and Brown himself was among the 
first to abandon the old masters and enroll under the new 
ones. His writings contributed very largely to their gen- 
eral acceptance in Great Britain. In 1827 he was appointed 
keeper of the botanical department of the British Museum. 
In 1834 he was awarded the degree of D.C.L. by Oxford, 
and in 1839 the Copley medal of the Royal Society. 

Although fully entitled to rank as a collecting botanist 
of high ability, Brown’s fame will rest mainly on the fact 
that he was the first to recognize, and to announce in 1831, 
that the cell nucleus was the life unit of the vegetable 
world, just as already it had been shown to bear that rela- 
tion to animal structure and tissue. His discovery was 
quickly followed up and extended by the botanist Schleiden, 
and the zoologist Schwann; with the effect of making it 
clear that all forms of organie life, from the lowest to the 
highest, are built up on one and the same system, in which 
the cell, with its centrally placed nucleus of protoplasm, 
surrounded by the cytoplasm, is the unit. It is of micro- 
scopic size, and essentially the same in plants and animals, 
including man. The substance called plasm, which exists 
in both the nucleus and cytoplasm, is continually in mo- 
tion so long as life exists. 

Protoplasm is mainly composed of carbon, hydrogen, oxy- 
gen and nitrogen, the other ingredients usually present 
in minor quantities being sulphur, phosphorus, potassium, 
and sometimes a few other of the elements. But almost 
nothing can be learned of the nature of this substance by 
making a chemical analysis of it, for the instant that proc- 
ess begins its death occurs. It is the belief of physiologists 


The Exghteenth Century 221 


that the evidence it gives of life in its motion is a molecular 
phenomenon, and must be studied mechanically as such. 
During recent years a very extensive literature has grown 
up on organic cells, which is absorbingly interesting to stu- 
dents of vital phenomena; but it cannot be claimed that as 
yet our knowledge of the nature of protoplasm is much 
more than of a preliminary kind. 


YOUNG (1773-1829) 


PHYSICS 


THOMAS YOUNG was reared in Milverton, England, of 
Quaker parentage, and acquired his education at a small 
eountry school in the vicinity of his home, and later under 
a private tutor. At the age of twenty-one he began the 
study of medicine in London, continuing afterwards at 
Edinburgh, and finishing up at Gottingen in Germany, 
where he received his degree. He began to practice in 1799. 
In 1801 he was appointed professor of natural philosophy 
at the Royal Institution, and in the following year was 
elected Foreign Secretary of the Royal Society, a position 
which he retained for the remainder of his life. 

Two notable discoveries stand to his credit, in the annals 
of the advance of knowledge. The first of these was a cor- 
rect description of the cause of astigmatism, and with it 
a statement of the optical constants of the human eye. 
These have earned for him the title of the founder of the 
science of physiological opties. 

The second was the demonstration of the undulatory 
theory of light, which had been suggested tentatively by 
Huygens in 1690. In making this demonstration he used 
the principle of interference. His announcement was that 
‘‘radiant light consisted of undulation of the luminiferous 
ether.’’ Up to the present time the existence of this 
‘‘ether’’ has not been scientifically demonstrated, though 
believed in by most scientists. At present it is regarded 
by advocates of the theory of Relativity, to be unneces- 
sary, aS an explanatory hypothesis, though the effects 
ascribed to it are not questioned or in doubt. 


222 Beacon Lights of Science 


Astigmatism is the name given to that defect in vision 
which is due to more or less absence of perfect symmetry 
in the construction of the two eyes; that is, the lenses are 
not similarly placed, or are of different size, thickness or 
clearness, or the corneas (their outward protective horny 
shield) are of different curvatures, or vary in degree of 
transparency. The effect produced on the brain is a dis- 
torted image of the object viewed. Some slight and neglig- 
ible degree of astigmatism probably exists in all eyes. A 
simple test is to perforate a card with a pin, and examine 
the aperture so made alternately with each eye, and at 
varying distances. If at any position or to either eye the 
circular puncture appears elliptical in outline, astigmatism 
exists. Generally, when the exact cause of the trouble is 
ascertained, it is easily corrected by the use of properly 
constructed spectacles. 


BELL (1774-1842) 


ANATOMY 


CHARLES Betu lived in Edinburgh, Seotland, and was 
educated in that city for the medical profession. At the 
age of twenty-three he became a member of the faculty of 
the Edinburgh College of Surgeons. In 1804 he moved to 
London, and for some years was a lecturer of the highest 
repute at the hospital clinics and medical schools of that 
city and vicinity. 

To acquire a more thorough knowledge of the effects ot 
gunshot wounds, he visited the hospitals on the south coasts 
of England, where the wounded from the battle of Corunna 
were under treatment; and again those in Brussels, to 
which the wounded were brought after the battle of Water- 
loo. In 1824 he became professor of anatomy at the Royal 
College in London, and subsequently a member of the 
Council. On the establishment of the London University 
in 1826, he was placed at the head of the department of 
medicine. In 1829 he received the medal of the Royal 
Society for his discoveries in anatomy, and in 1831, in 


The Exghteenth Century oo5 


company with four other notables of the day, he was given 
the order of knighthood. He was a voluminous writer on 
his subject, but is especially distinguished by his principal 
discovery in anatomy, a generalization on the functions of 
the nervous system which, once clearly recognized, led 
the way to other discoveries and conclusions of the greatest 
importanee. The principle he revealed is expressed con- 
cisely as follows: 

‘‘The anterior spinal nerve roots belong to motor nerves, 
and the posterior ones to sensory nerves.’’ 

The development of the nervous system in man and in 
all animals begins at a very early stage of embryonic life. 
The evolution of the spinal cord is the first visible step, 
and at the upper end of this the brain begins to make its 
appearance. When the cord is well developed, it begins to 
send out branches to all parts of the embryo, which divide 
and subdivide again and again, and terminate finally in 
minute fibers, but these do not extend into the hair or nails, 
nor their analogues the feathers, claws, hoofs, scales, ete. 
Those which are to serve the purpose of conveying to the 
brain the stimuli received from the outer world by the 
sense of touch, are all rooted in the back parts of the spinal 
cord, and terminate just inside of the outer layer of the 
skin. Those which control the voluntary and involuntary 
movements of the body, proceed from the front areas of 
the spinal cord, and from there advance to every organ 
and muscle. 


AMPERE (1775-1836) 


ELECTRICITY 


ANDRE MARIE AMPERE was a resident of Lyons, France, 
during the troublous times of the French Revolution. At 
the age of eighteen, the execution of his father under the 
guillotine for political reasons, affected him deeply, and 
saddened his whole life. Having received a good education, 
and being compelled to support himself, he undertook tu- 
torial work in mathematics at first, and later became pro- 


Q94 Beacon LInghts of Scrence 


fessor of physics at the central school at Bourg, near Lyons. 
From there, he advanced to a similar position in the Poly- 
technique school in Paris, and later took the chair of exper- 
imental physics in the Collége de France, a position which 
he retained during the balance of his life. In 1814 he was 
elected a member of the Academy of Science. 

The high rank of Ampére among discoverers, is due in 
part to his clear exposition of the theory of electro-dy- 
namics, but mainly to his demonstration of the identity 
of the phenomena of electricity and magnetism. And 
while his explanation of the latter, which was that ‘‘an 
electrical current is present in each molecule of a magne- 
tized body, and flows in a fixed path,’’ is not accepted at 
the present time, no other explanation has since been ad- 
vaneed which is considered wholly satisfactory. But there 
remains no question in the minds of scientists, that when 
the correct explanation is given, it will confirm Ampére’s 
theory of the identity of the two forms of force. 

There is no doubt that magnetism is a molecular prop- 
erty. Ifa bar magnet is broken in two, each half becomes 
at once a complete magnet, with a positive pole at one end 
and a negative pole at the other. Further, when a bar 
of soft iron is magnetized, its volume and elasticity 
changes; and if, by the action of an alternating current, it 
is rapidly magnetized and demagnetized, its temperature 
rises. 

Ampére was the inventor of the astatic compass, which 
was employed in the early form of galvanometers, to de- 
tect very weak currents of electricity. He also originated 
the theory that electrical currents circulate in the earth, 
traveling in the same direction as the rotational movement 
(west to east), thus causing it to be a gigantic magnet, 
which, in its turn, would account for the movements of the 
mariners’ compass. In recognition of the great value of 
his studies in the electrical sciences, his name, by interna- 
tional agreement, has been adopted to designate the unit 
of strength or intensity of an electrical current; that is, 
the quantity of electricity which passes the cross-section 
of a conductor in one second of time. Or, expressed differ- 


The Eighteenth Century 225 


ently, it is the current which flows through a conductor 
whose resistance is one ohm, and between the two ends of 
which the unit difference of potentials, one volt, is main- 
tained. 

He died at Marseilles at the age of 61, greatly mourned 
among his friends and scientists generally. 


AVOGADRO (1776-1856) 


PHYSICS 


AMADEO AYOGADRO was a native of Turin, Italy, and after 
acquiring an excellent education, became a student of the 
physical sciences. In 1811 he announced his great discov- 
ery in connection with the molecular constitution of gases, 
which is known as Avogadro’s law, as follows: 

‘Under similar conditions of temperature and pressure, 
equal volumes of gases and vapors contain equal numbers 
of molecules.’’ 

Avogadro was a contemporary of Gay-Lussac, who had 
discovered the law of combining volumes, and the law an- 
nounced by the former was a logical deduction from that 
enunciated by the latter. But, unlike Gay-Lussae’s, which 
ean be demonstrated experimentally with ease, Avogadro’s 
law was at the time incapable of such proof, because of the 
minuteness of the molecule, and the impossibility then of 
counting those existing in even the smallest of visible vol- 
umes. 

But though Gay-Lussae at once accepted the deduction 
made by Avogadro, and Ampére a few years later (1814), 
it was some time before it was generally accepted. 

The practical importance of the discovery lies in the 
fact that it permits of ascertaining the relative weights of 
the molecules of all substances that are capable of being 
examined in the condition of a gas or vapor. They are 
comparatively few in number, but as the entire structure 
of modern applied chemistry rests on our knowledge of 
gaseous phenomena, the importance of the law is evident. 
It will also be easily understood that, as in gases under 


226 Beacon Lights of Science 


normal conditions the molecules must be farther apart than 
in solids or liquids, their mutual interactions must be 
comparatively slight, and so the number of causes deter- 
mining their properties must be fewer, the properties them- 
selves less complex, and hence more easily understood. 
Thus the study of gases is the simplest and most direct 
way by which to approach the study of matter in general. 
In 1886 the Dutch physicist Van’t Hoff demonstrated that 
the law was equally applicable to substances in solution. 

Since Avogadro’s day it has become possible to actually 
count the number of molecules in a given volume of rarefied 
gas. The result has demonstrated the accuracy of the law 
he enunciated over a century previously. The story of this 
journey into an unseen world and its accomplishments is 
interesting, and not so difficult to understand as might be 
imagined. But some preliminary explanations will be 
helpful. 

The ultimate forms of matter as known until recently, 
have been the elementary atoms; and while these have 
now been resolved into combinations of electrons and pro- 
tons, and when so resolved have passed from the domain of 
the chemist into that of the physicist, the atoms still con- 
stitute the only material of nature upon which, as matter, 
the chemist operates. In fact, he has comparatively little 
to do even with them. For, of the eighty-eight known, in 
less than one-quarter is the molecular condition identical 
with the atomic, and six of these are the inert gases, which 
refuse to react chemically either with the other elements or 
with themselves. In the majority of cases two or more 
atoms of the same kind invariably travel and act chemi- 
eally together. These molecular families—as they might 
be called, together with the few bachelor or spinster ele- 
ments who insist on traveling alone, constitute the citizenry 
of the molecular world which is the operative domain of 
the chemist. 

In all cases these particles of matter (the molecules) are 
extremely small, so minute in fact as to be invisible under 
the highest power of the microscope; yet, as stated, their 
dimensions and weight, and the number of them in a given 


The Eighteenth Century axe 


volume, have been determined with a high degree of ac- 
curacy. 

One of the fundamental properties of matter when in the 
easeous condition, that has been experimentally demon- 
strated in innumerable instances to be true, is that ‘‘at any 
given temperature its volume (the space it will occupy) 
is inversely proportional to the pressure under which it 
exists at the time.’’ Or, expressed in another way, ‘‘that 
the product of the pressure under these conditions and the 
volume occupied is a constant,’’ that is, for each gas, an 
unchangeable quantity. These statements mean that if a 
gas is confined in a gas-tight container, it will exert a pres- 
sure against the interior of its walls in exact proportion 
to the degree of compression applied in putting it there. 
Or, if no force is used in putting it there, no pressure will 
be exerted against the walls except that due to its weight. 
The weight of an empty, uncorked bottle is plainly that of 
the bottle, plus that of the air it contains, and when the 
latter is unconfined it expands until the force of gravita- 
tion stops the process. It is then in the state called ‘‘free 
air’’ by the mechanical engineer. Now the molecules of a 
gas—say the amosphere—are in constant vibratory motion 
back and forth in short paths, and are only prevented from 
traveling in longer paths by the attraction exerted by that 
ereat mass of matter near them, the earth. Let us now 
consider the case of a single molecule. 

Under the above assumptions the exact space it occupies 
is determined by the length of its little vibratory journeys, 
minus its own size, which is so minute as to be practically 
negligible. If we begin to compress this air in the bottle, 
at once the travel of each molecule begins to be shortened, 
that is, the molecules are packed closer to each other and, 
in their turn, begin to exert pressure on the walls of the 
bottle. Continuing the compression, the pressure on the 
walls will steadily increase as the molecules are forced to- 
gether more closely, until at last a point will be reached 
when they have been driven so near to each other that their 
mutual attraction is no longer negligible, and becomes of 
enough importance to neutralize to some extent the pres- 


228 Beacon Lights of Science 


sure the gas is exerting on the walls of the vessel. Just 
before this state of affairs is reached we have, in the ves- 
sel, what may be called the ‘‘ideal pressure,’’ that is, the 
pressure determined alone by the vibratory movements of 
the molecules, undiminished by their mutual attraction, 
which plainly gives the length of the journey of each, and 
from which may be ealeulated the volume within which 
each one is free to move. 

Returning now to the law enunciated at first, to the 
effect that ‘‘the product of the volume occupied by a gas 
and the pressure it then exerts on the walls of its container 
is a constant,’’ it is plain that if the figure which represents 
that constant is known (which is the ease, though it is 
different for each kind of gas), the dimensions of the vol- 
ume in which each molecule is vibrating can be determined. 
Then, if the total volume within which the gas is confined 
is divided by the volume within which each molecule is 
vibrating, the quotient must represent the number of mole- 
cules present. Finally, if the total volume under confine- 
ment is divided by the number of molecules therein, the 
quotient must represent the volume of space actually occu- 
pied by each molecule. 

Now let the bottle and its contents be weighed. From 
this deduct the weight of the bottle. The remainder will 
be the weight of the molecules. Knowing their number it 
is a simple matter to ascertain the weight of one of them. 
We now have the number in the bottle and the weight of 
each. From these, by a process difficult to describe without 
employing algebraic formulae, the fraction of the volume 
of a gas actually occupied by its molecules can be deter- 
mined which, under the assumption that the molecule is 
a sphere, will permit of its size to be calculated. Other 
considerations rather too complicated to be explained here 
have led to the conclusion that under given conditions of 
heat and pressure one cubic meter of any gas contains ap- 
proximately 54,000,000,000,000,000 molecules. Since one 
cubic meter of hydrogen weighs 0.00009 milligram, the 
weight of a single one of them should be 0.000,000,000,- 
000,000,000,000,016,6 milligram. 


The Exghteenth Century 229 


GAUSS (1777-1855) 


ASTRONOMY 


Karu FriepricH Gauss was the son of a day laborer, of 
Brunswick, Germany. Nevertheless, he acquired an excel- 
lent education, and graduated with honors at the University 
of Gottingen in 1798, his specialty being mathematics. Be- 
fore leaving there, he had solved for the first time the prob- 
lem of dividing a circle into seventeen equal ares, by al- 
ready known and simple geometrical principles—the first 
extension of the ancient Greek knowledge in this particular. 

On the first day (or night) of the 19th century, the 
astronomer Piazzi at Palermo discovered Ceres, the first of 
the planetoids, and continued his observations on this small 
member of the solar system until February 13th, when 
forced to discontinue them because of a serious illness. By 
the time the news of the discovery had reached the ears of 
other European observers, not only had the little planet 
moved so far away from its last observed position, that it 
could not be found, but had approached so close to the sun 
that observation was impossible. Nor did the astronomers 
of the day possess then a method of computing an orbit, 
from notes of position extending over so short a period of 
time as the five or six weeks—with frequent interruptions 
from cloudy weather—that had been allowed to Piazzi. 
Hence it was feared that by the time it became visible 
again, it could not be located. When Gauss was apprised 
of the situation, he devised a method of computation from 
Piazzi’s notes, which enabled him to calculate the planet’s 
path so accurately, that at the end of the year it was 
picked up again almost exactly in the position his figures 
assigned. His monograph on this problem, published in 
1809, and entitled ‘‘Theoria Motus Corporum Coelestium,’’ 
established his reputation as the first astronomical mathe- 
matician of his time. 

Gauss is regarded as the discoverer of the mathematical 
theory of electricity ; and he enjoys with Henry the credit 
of being among the first to employ the telegraphic art 


230 Beacon Lights of Scrence 


when, in association with Weber, he established in 1833, a 
wire connection between the magnetic and astronomical 
observatories at Géttingen, and employed it for signaling 
from one to the other by sound. 

Gauss is also remembered as the developer of the mathe- 
matical device known as the Method of Least Squares, the 
application of the theory of probabilities to the deduction 
of the most probable value from a number of observations 
or results each of which, from the nature of the case, is 
liable to be slightly in error. The germ of the idea origi- 
nated with Legendre in 1805, and was used by him in eal- 
culating the orbits of certain comets, but he gave no proofs 
of its accuracy, nor did he analyze its operations deeply 
enough to be prepared to formulate the mathematical law 
at its foundation. Adrian, a mathematical writer, gave 
two proofs of it in 1808, and Gauss a third in the following 
year, and then, by analysis, placed the theory and its 
methods of application so clearly before the mathematical 
world, that its value was at once clearly recognized. A 
simple illustration will reveal its use. Assume a circum- 
ference of size which is bisected by a diameter. Assume 
this circumference and the two semi-circumferences to be 
instrumentally measured. There have then been three 
measurements, none of which can be positively guaranteed 
as absolutely accurate. What then is the most probable 
true measure? This the Method of Least Squares gives. In 
astronomical work problems of this nature, but vastly more 
complicated, are of frequent occurrence, and their solution 
with absolute accuracy admittedly impossible, owing to 
defects of vision and of instruments. Yet it is highly de- 
sirable to approximate accuracy as closely as is mathemati- 
cally possible. Hence, a large number of observations are 
taken and the measurements they yield are submitted with 
confidence to the Method of Least Squares. The result is 
not the average, but the most probable approach to the 
true value. 


The Enghteenth Century 231 


DAVY (1778-1829) 


CHEMISTRY 


HumpuHry Davy was a native of Penzance in England, 
his father being a carver in wood. He attended school at 
Truro up to the age of sixteen, and was then apprenticed 
to a surgeon and apothecary of his home town. During this 
period of his life he was an avid reader in many lines of 
speculative thought, but ultimately found himself more 
attracted to natural philosophy than anything else, and 
especially in that department or branch of it which was 
the budding science of chemistry at the time. Becoming 
associated in his nineteenth year as an assistant to a Doctor 
Beddoes at Bristol, who conducted an establishment called 
a ‘‘pneumatiec institute,’’ where patients were treated for 
ills of the respiratory system, by causing them to inhale 
medicated air; he became interested in the various fumes 
employed, and finally discovered, through an experience 
which nearly cost him his life, the exhilarating and an- 
aesthetic properties of nitrous-oxide, which was at first 
known as ‘‘laughing gas.’’ After investigating the sub- 
ject thoroughly, he published an account of his experi- 
ments, which aroused so much interest, that he was ap- 
pointed in 1801 a lecturer at the Royal Institution of Lon- 
don. Here his natural platform ability and charm of man- 
ner, coupled with the novelty of his subject, attracted large 
and brilliant audiences, and won him the appointment of 
professor of chemistry. Yet it was nearly forty years 
thereafter before anaesthetics, as a recognized valuable 
department of surgery, became established, and even then 
for some years only in dentistry. Davy himself does not 
seem to have appreciated the importance of his discovery, 
for in his lectures and writings he turned quickly to other 
subjects, where he made important and interesting an- 
nouncements. Perhaps the most remarkable of these was 
contained in his paper entitled ‘‘On Some Chemical 
Agencies in Electricity,’’ which was read in 1806. In this, 
he advanced the theory that chemical affinity was nothing 


232 Beacon Lights of Science 


but the mutual electrical attraction of the ultimate particles 
of matter, the atoms. He reached this conclusion after 
meeting with success in extracting the metals potassium, 
sodium, strontium and magnesium, from their oxides pot- 
ash, soda, strontia and magnesia. And while, on account 
of the limited chemical and electrical knowledge of his day, 
the theory could not be experimentally demonstrated, ex- 
cept in a few simple eases, and was afterwards set aside 
and forgotten, yet at the present time it is recognized as 
one of the fundamental principles of matter, and appears 
to have been demonstrated beyond all question. 

In 1812 Davy was knighted. In 1815 he invented his 
‘‘safety lamp,’’ for use in coal mines. In 1825 he suffered 
a paralytic stroke, affecting his right side, which a few 
years thereafter resulted in his death at the early age of 51. 
He is rightly regarded as one of the great men of science 
of his day. 


GAY-LUSSAC (1778-1850) 


CHEMISTRY 


Louis JOSEPH GAy-LUSsAc was reared at Sainte Leonard- 
le Noblat in central France, and was educated at the Ecole 
Polytechnique, and after graduating became the assistant 
of the chemist, Berthollet. 

In 1804, in association with Biot, the astronomer, he 
was commissioned by the French Institute to make a bal- 
loon ascension, to study the temperature, humidity and 
composition of the air at high altitudes, and to ascertain 
whether the magnetic force existed at considerable distance 
above the surface of the earth. They succeeded in reaching 
a height of 28,000 feet, in securing samples of the air there, 
in registering temperature and humidity at various stages 
of the journey, and in taking observations which showed 
that the magnetic activity was as great at the summit of 
their flight as on the surface of the ground. Somewhat 
later, while investigating the chemical composition of the 
air collected, he had occasion to measure the volume of 


The Eighteenth Century 233 


the two gases (hydrogen and oxygen) which, when united 
chemically, form water, and determined the proportions 
as invariably two of the former to one of the latter. This 
impressed him greatly, and led him to make numerous 
experiments along the same lines with other gases, the re- 
sult of which was his announcement in 1808, of the ‘‘ Law 
of Combining Volumes,’’ which is one of the most impor- 
tant in the whole domain of chemistry. In recognition of 
this fundamental discovery, he was appointed to the chair 
of chemistry at the Ecole Polytechnique. In 1818 he took 
charge of the government gunpowder manufactory, and in 
1829 of the Mint. Ten years later he was created a peer 
of the realm. 

His law may be stated as follows: 

‘‘When two or more gases react chemically with each 
other, their reacting volumes bear to each other a ratio 
that can be expressed by small integral numbers.’’ Thus, 
when hydrogen (H), and chlorine (Cl), unite to form 
hydrochloric acid (HCl), the volumes of the reacting 
gases are equal, that is, their ratio is 1 to 1. Similarly, 
equal volumes of gaseous hydrochloric acid and ammonia 
combine to form ammonium chloride. In the formation 
of water (H,O), the two gases unite in the simple ratio 
of 2 to 1. 

This law was soon found to apply to all the elements, 
solid, liquid and gaseous, and to all the combinations which 
occur between them. Thus, pure limestone always consists of 
one part of the metal calcium combined with one part of the 
non-metal carbon, and three parts of the gas oxygen; cane 
sugar of twelve parts of carbon, combined with twenty-two 
parts of the gas hydrogen, and eleven parts of the gas oxy- 
gen; red iron rust of two parts of the metal iron combined 
with three parts of oxygen. In other words, the elements in- 
variably unite with each other—if at all—in proportions 
which may be expressed by comparatively small integral 
numbers. Fractional combinations are unknown, and are 
believed to be non-existent. Common table salt when pure, 
if analyzed, will invariably yield exactly one part each 
of the metal sodium and of the gas chlorine,. Iron, it 


234 Beacon Lights of Science 


is true, will unite in three different ways with oxygen, 
ealled respectively the protoxide, the sesquioxide and the 
peroxide. But in each case the resulting compound is a 
totally different substance in appearance and properties 
from the other two, and in all three the proportions in 
which the iron and the oxygen unite are expressible by 
small whole numbers. 

Gay-Lussae was the discoverer of the non-metallic ele- 
ment boron, which is the principal component of the well- 
known substance borax. He devised new and improved 
methods for the isolation and separation of the metals sod- 
ium and potassium. He was the first to produce iodic and 
hydriodice acids from iodine, and to make the very deadly 
but highly useful compound of equal parts of carbon and 
nitrogen that is known as cyanogen. 


BERZELIUS (1779-1848) 


CHEMISTRY 


JONS JAKOB BERZELIUS was a native of Westerlésa in 
Sweden, and after graduating at the University of Upsala 
he went to Stockholm, and devoted himself to teaching, and 
to research in chemistry and medicine. In 1806 he was 
appointed lecturer in the former science at the Military 
Academy, and in the following year, professor of medicine 
and pharmacy. Shortly afterwards he became a member 
of the Stockholm Academy of Science, and from 1818 until 
his death was its secretary. 

To a very large extent, the science of inorganic chemistry 
owes its foundation and growth to the labors of Berzelius. 
He was a keen and tireless investigator, the discoverer of 
the elements cerium, selenium and thorium, and the first 
to prepare and exhibit for examination, samples of many of 
the rare metals and elements, such as columbium, tantalum 
and silicon. The multitude of analyses made by him, and 
their accurate character, established the laws of the com- 
binations of the elements then known with each other on a 
foundation that had not previously been approached. He 


The Exghteenth Century 235 


also was largely instrumental in extending and perfecting 
the system of nomenclature now employed. He was an 
expert in the use of the blowpipe for the qualitative analy- 
sis of minerals in the field, and practically the founder of 
that branch of the science. 

In 1812 he advanced a general theory of chemical com- 
binations, based on the assumption that the atoms of the 
elements are charged with electricity, some being electro- 
positive, and some electro-negative. To hydrogen was as- 
signed a central position in the scheme, because it seemed 
eapable of yielding many varieties of compounds. Further, 
the extreme electro-positive position was assigned to the 
metal potassium, and the extreme electro-negative to the 
gas oxygen. This theory, further elaborated, was actively 
advocated by him, as an explanation of all chemical phe- 
nomena, and for a time was almost universally accepted. 
But between 1830 and 1840, it became evident that, as out- 
lined by him, it was not a correct statement of the phe- 
nomena under consideration, and was gradually abandoned, 
though Berzelius himself clung to it throughout his life. 
During recent years it has become apparent that there was 
some prophetic truth in it, and in somewhat modified form 
it is in process of revival, especially since the atoms of his 
day have been split up into electrons, and have been shown 
to be constituted practically of electrical units, and nothing 
else. 


SILLIMAN (1779-1864) 


GEOLOGY 


BENJAMIN SILLIMAN, a native of the State of Connecti- 
eut, and the son of a general who served in the Revolu- 
tionary War, was a graduate of Yale University where, 
after serving for several years as a tutor, he was appointed 
in 1802 a full professor of chemistry, geology, mineralogy 
and pharmacy; a combination of instructional duties which 
not only indicates his broad proficiency as a teacher, but 
also the unspecialized nature of the scientific curriculum, 


236 Beacon Lights of Science 


even in institutions of high standing, in the early years of 
the last century. He was a man of unusual personal charm, 
highly honored by all who knew him for his ability, and 
greatly admired by his pupils. For sixty-two years he 
filled this position, the last eleven as professor emeritus. 
During that long ineumbeney, as might be expected, his 
instructional duties crystallized gradually towards geology, 
and finally were confined entirely to that subject, chem- 
istry, mineralogy and pharmacy being taken over by others. 

In the early years of his career he was a confirmed be- 
liever in the geological views held and taught by Werner 
at Freiberg; and when Lyell’s great work ‘‘The Principles 
of Geology’’ appeared (1830-1833), in which totally dif- 
ferent explanations were advanced to account for the ob- 
served facts in that branch of study, he was unable to fall 
in line with the new trend of thought, though many passages 
in his writings, and even in his lectures, may be cited, that 
indicate doubt as to Werner’s theories. One of these, dated 
in 1821, is of peculiar interest. After giving a description 
of the vast areas in New England, New York and eastern 
Canada, over which are found the rounded boulders and 
pebbles, and the ridges and sheets of gravel, now sum- 
marized under the general name of ‘‘glacial drift,’’ and 
accounted for by the well-established theory of continental 
glaciation, and which by Werner were ascribed to the 
Noachian Deluge, he wrote—‘‘these have ever struck me 
as among the most interesting of geological occurrences, 
and as being very inadequately accounted for by existing 
theories. ’’ 

In 1818 he founded, and for twenty years edited, the 
‘“American Journal of Science,’’? which was continued by 
his son, and from its inception has ranked as a leading 
technical periodical. He was the inventor, with Dr. Hare, 
of the compound blowpipe, an improvement on the instru- 
ment designed by Plattner of the Frieberg Mining Acad- 
emy in Saxony, a tool which was much in use during the 
last century among mineralogists, in the preliminary exami- 
nation of ores of the metals, and of rocks in general. He 
was the first to identify that rather unusual variety of 


The Eighteenth Century 237 


aluminum silicate which occurs in the form of long and 
slender crystals of a greenish brown color in the older rocks, 
and which, in his honor, was given the name of sillimanite. 

As a lecturer on geology he was always able to command 
a large audience, and during his active years gave many 
courses that were very effective in disseminating among the 
people a knowledge of the discoveries constantly being made 
in those branches of science which he had made his spe- 
cialty. And, like his great contemporary Faraday, he pos- 
sessed the ability of talking to the people on technical sub- 
jects, in language that all could understand. 


AUDUBON (1780-1851) 


NATURAL HISTORY 


JOHN JAMES AUDUBON was born at Mandeville, Louisi- 
ana, when that part of the United States was a colony of 
Spain. His father was a wealthy Frenchman, the owner 
of large estates in Santo Domingo. His mother was of 
pure Spanish ancestry. Many years before Louisiana 
passed from the control of Spain and France, the elder 
Audubon moved his family to France, and so the child- 
hood and youth of John James was passed there. He re- 
ceived an excellent education, including special instruction 
in drawing under the noted artist David. During the 
American Revolutionary War his father acquired an estate 
near the city of Philadelphia. When the French Revolution 
broke out in 1789 he gave this land to the young man, who 
came to America in the following year and took possession 
of it. Here he lived for ten years, devoting the most of his 
time to the study of wild bird life, in which that part of 
the New World was then particularly rich. In 1808 he 
married, and finding the rapid settling up of Pennsylvania 
a serious bar to the prosecution of his studies in natural 
history, he sold his farm and moved across the Allegheny 
mountains into the new state of Kentucky, where he rein- 
vested in land and became ostensibly a pioneer farmer. 

But Audubon was in no sense a business man, nor a 


238 Beacon Lights of Science 


worker of any kind. With him the love of nature, and es- 
pecially of avian life, was an obsession. In a comparatively 
few years he had lost all his rea] estate and other property, 
and was driven to the giving of drawing and even of danc- 
ing and fencing lessons, and the making of portraits, for 
support, and every hour that could be spared from these 
uncongenial but necessary labors was devoted to his studies 
in the untouched forests and beautiful valleys of the new 
land into which he had emigrated. The result was a col- 
lection of drawings which, of its kind, has never since been 
approached in accuracy and completeness, for he was a 
careful artist. With each sketch he made voluminous notes 
of colors and habits so far as he could obtain them. 
Throughout his long struggle for maintenance amid the 
erude conditions of frontier life, and under the handicap 
of an artistic disposition that would not be denied, he was 
so faithfully aided and encouraged by his devoted wife, 
that in 1824 he was able to take his collection to Philadel- 
phia, which by then had become an intellectual center of 
considerable note. There he found friends who recognized 
its value, and who provided the means to take it to London 
in 1827, where he quickly was able to publish it under the 
title of ‘‘Birds of America.’’ The prints, beautifully exe- 
cuted, came from the press in folio parts, at the rate of 
about five parts per annum, during the decade between 
1828 and 1838, and proved so overwhelmingly a commercial 
as well as artistic success, that he was relieved from all 
financial worries for the balance of his life. In 1842 he 
purchased a small estate on the Hudson river (now within 
the limits of the city of New York), where he passed the 
remainder of his life with his two sons and their families. 
Audubon would hardly be regarded at the present time 
as a scientist, nor even an artist of note. Yet his love of 
nature, and his devotion to that aspect of it which su- 
premely enlisted his enthusiasm, fully warrants the inclu- 
sion of the story of his life and of his work in any list of 
those who have taken part in adding materially to the 
world’s stock of classified knowledge. He was a man of 
simple and kindly disposition, attractive in person and in 


The Exghteenth Century 239 


personality. In his prime he displayed all the vigor, vir- 
ility and endurance of the typical pioneer. In his old age 
he was the pride of his descendants, and an honored friend 
of all who enjoyed the pleasure of his acquaintance. The 
actual results that he left to the world were not so impor: 
tant as the example of devotion to an ideal. Yet but for 
his labors we should know much less than we do of the 
abundant and very remarkable bird life which character- 
ized the eastern parts of the North American continent in 
the years when it first became known to the white man. 
In contrast, it may be understood how much has been lost 
forever because, when the Spanish and Portuguese overran 
the rest of the New World there was no one with them of 
the type of Audubon to record its wild life except in words. 


BREWSTER (1781-1868) 


PHYSICS 


Davip BREWSTER’s birthplace was Jedburgh in Scotland, 
and he was. educated for the Church. But being more 
attracted to science than theology, he became in 1808 the 
editor of the Edinburgh Encyclopedia, to which he also 
made extensive contributions. He was particularly inter- 
ested in the phenomena of optics, was the inventor of the 
kaleidoscope, and published a book on it. Although this 
device is but a scientific toy, its ability to produce an infi- 
nite number of symmetrical figures has been extensively 
taken advantage of, to secure suitable and attractive de- 
sions and patterns for carpets, wall papers and other 
fabrics. He shares, with Wheatstone, in the invention of 
the stereoscope which, as devised by the latter in 1838, 
employed reflecting mirrors instead of lenses, and was 
successful only so long as the pictures to be operated upon 
were confined to representations of geometrical objects, 
which could be readily duplicated. But the exact dupli- 
cation of complex objects, such as natural scenery, is be- 
yond the skill of an artist, and at the time photography 
had not been developed to the point where it could be 


240 Beacon Lights of Science 


employed for that purpose. Brewster took up the mat- 
ter in 1849, and substituted lenses for the Wheatstone mir- 
rors, and being then able to resort to the photographic art 
for his pictures, produced remarkably satisfactory results. 

His scientific work brought him many well-deserved 
honors. In 1815 he won the Copley medal for optical 
investigations, and in the following year he received half 
the prize bestowed by the French Institute, in recognition 
ef important discoveries made in physics during the two 
preceding years. In 1819 he received the Rumford gold 
and silver medals, for his discoveries connected with the 
polarization of light. He was knighted in 1831. In 1849, 
on the death of Berzelius, he was elected one of the eight 
{fcreign associates of the French Institute. He was also a 
member of the scientific Academies of St. Petersburg, Ber- 
lin, Copenhagen and Stockholm, and an associate of the 
National Academy of Sciences of the United States. He 
was a voluminous writer. 

The principle on which the stereoscope operates may be 
easily understood by looking at any solid object with one 
eye closed. It then gives merely the impression of a flat 
picture on a flat background. But when viewed with both 
eyes its three-dimensional quality is at once apparent. The 
reason is simple. The two eyes being separated hori- 
zontally by a space of several inches, we see with the right 
eye more of the right-hand side of a body under inspection 
than the left eye does, and the latter sees more of its left 
hand side than does the right eye. The two, operating 
together, produce the effect in the mind of a composite 
picture, in which we see around the corner—so to speak— 
on both sides of the object, with the result that it stands 
out in relief from its background. 

The Brewster stereoscope employs two identical pictures 
of the object to be viewed. In front of them, on a sliding 
frame properly shielded, is set the two halves of a double 
convex lens, with their thin edges adjacent. Through this 
eyepiece the observer looks, and when their position is 
adjusted to the proper focus for the individual, the two 
pictures blend perfectly into one, and the effect of relief 


The Eighteenth Century 241 


obtained naturally by the eye is now intensified, so that 
even distant objects in them, which the eye alone would 
hardly have the power to draw out of the background, are 
brought strongly into relief. 


BESSEL (1784-1846) 


ASTRONOMY 


FRIEDRICH WILHELM BrESSEL was a native of Minden, 
Germany, and was destined by his father for a commercial 
life. But at a very early age he exhibited so strong an 
inclination to science, and particularly to astronomy, that 
he was ultimately and very wisely allowed to follow his 
natural tendencies. Having been given an excellent edu- 
cation in the fundamentals, he read and studied the higher 
branches by himself, and by 1810 his standing among obser- 
vational astronomers had become so high that he was of- 
fered the directorship of the observatory at K6nigsberg in 
Hast Prussia, and the chair of astronomy in the university 
there. In these positions he added greatly to his reputa- 
tion by the numerous discoveries made in the observatory, 
and by the publication of two notable works, namely, ‘‘ Fun- 
damenta Astronomiae’’ in 1818, and ‘‘Tabulae Regiomon- 
tanae’’ in 1830, both of which were unusually meritorious 
literary and scientific productions for their day. 

His great achievement was the determination of the 
parallax of the star 61-Cygni. His method was not only 
entirely new, but extremely ingenious. He selected this 
particular star, because he suspected, for various reasons, 
that it was one of the nearest to the solar system, and hence 
might have a parallax capable of being measured with the 
heliometer. He then proceeded to determine every clear 
night, its position relative to two neighboring very small 
and dim stars, which he selected for the purpose, because 
he concluded they were so immeasurably farther away, 
that no change in their position could be detected. Ac- 
cordingly, as he had hoped, he found that 61-Cygni was 
moving, with respect to these two, and, in fact, was describ- 


Q42 Beacon Lights of Science 


ing a tiny elliptical curve in the sky, which was nothing 
more than a minute reproduction in space of the earth’s 
orbit around the sun. This made it clear that the star 
had an apparent motion, due to the real motion of the 
earth, and this proved to be large enough to be measurable 
by the heliometer. Having then the area of two ellipses, 
whose relative dimensions were identical, it became a simple 
matter of calculation as to how far apart they were. 61- 
Cygni was thus found to be distant from the earth the 
equivalent of 8.1 light years, which meant that it lies 
approximately 500,000 times as far away from us, as our 
central orb, the sun. . 

Bessel’s method is rightly regarded as one of the most 
ingenious in its conception, and famous in its results, in 
the annals of astronomical research. By its use, the par- 
allax of a large number of the stars have since been de- 
termined, and consequently their distance from our system. 


DULONG (1785-1838) 


CHEMISTRY 


PrerRE Louis DULONG was a native of France, and was 
educated at the Ecole Polytechnique in Paris where, in 
1820, he became professor of physics. In 1823 he was 
elected a member of the French Academy of Sciences. 

He is chiefly known in connection with the physical law 
which, in collaboration with Petit, they discovered, and 
which is known as the Dulong and Petit law. It runs as 
follows: 

‘‘The product of the specific heat of any element, when in 
the solid state, and its atomic weight, is (approximately) 
a constant.”’ 

The inference from this law—which is universally ac- 
cepted, but not yet explained—is that the atomic heat of 
all the elementary substances is practically identical. 

Each of the eight-eight elements that have so far been 
discovered, has a property which is called its atomic weight. 
It is expressed by a number, which may either be a whole 


The Eighteenth Century 243 


one, or one with a fraction. Thus, the atomic weight of 
oxygen being called 16 for the purpose of establishing 
a unit, that of carbon is 12; of gold 199.2; of lead 207; and 
of uranium, the heaviest element in the list, 238. These 
figures represent the relative weight (not the actual) as 
compared with that of the unit element oxygen, of the 
smallest amount of each that is capable of existing as a 
fixed quantity in a chemical compound or, as it is called, 
the atom. Thus common table salt is a compound of the 
metal sodium with the gas chlorine, and is expressed in the 
language of the chemist by the symbol ‘‘NaCl’’; in which 
the ‘‘Na’’ stands for the sodium (formerly known as 
natron) and the ‘‘Cl’’ for chlorine. The union of the two 
is expressed numerically by adding together the atomic 
weights of sodium (23) and chlorine (35.5), making the 
atomic weight of the compound 58.5. Pure water, which 
is a compound of the two gases hydrogen and oxygen, is 
symbolically expressed as ‘‘H,O, and numerically by the 
figure 18, which is the sum of 2 unit weights of hydrogen 
and 16, the unit weight of oxygen. 

Another property, possessed by all the elements, is known 
as their specific heat, by which is meant the amount of heat 
required to raise the temperature of any one of them one 
degree Centigrade under certain specified conditions. This 
is different for each of the elements, but has a much smaller 
range of values. Thus the specific heat of hydrogen—the 
lightest of the elements—is 3.4090, while that of platinum 
—one of the heaviest—is 0.032. 

Dulong and Petit’s discovery was to the effect that if 
the atomic weight figure of any element is multiplied by 
its specific heat figure, the product in all cases will be 
approximately a constant, that is, an identical figure. It 
is 6.4, and is called the atomic heat figure. 


CHEVREUL (1786-1889) 


CHEMISTRY 


MicHEL EuGtNE CHEVREUL was a native of Angers, 
France. Being the son of well-to-do parents, after com- 


244 Beacon Lights of Science 


pleting his primary studies, he was sent to Paris to spe- 
cialize in the physical sciences, and in 1813 was appointed 
professor of those branches at the Lycée Charlemagne. In 
1820 he became an ‘‘examiner’’ at the Ecole Polytechnique, 
and in 1824 director of the dyeing department of the 
Gobelin tapestry manufactory. In 1829 he was elected to 
the professorship of applied chemistry at the Museum of 
Natural History, a position which he retained for a half 
century, retiring only at the age of 93. 

His principal contribution to the advance of knowledge 
consisted in his successful investigation of the chemical na- 
ture of those products of the abattoir known as animal 
fats. He was the first to show that they were compounds 
of glycerin, with oleic, stearic and palmitic acids. Glycerin 
had been discovered by Scheele in 1784, but its usefulness 
was not immediately recognized, because no large source of 
it was known. When Chevreul found it in quantity in the 
animal fats, and in combination with the acids mentioned, 
a cheap and abundant supply of all was assured, in regard 
to the acids for the manufacture of soap, and as to the 
glycerin for the making of nitroglycerin. 

At the time soap was a high priced commodity, available 
only to a limited degree among the poor. It now became 
possible to produce it very cheaply. ‘As cleanliness has 
been ranked by a distinguished writer to be next to godli- 
ness in its benificent effects, the enormous value to the 
world of this part of his investigation is evident. Soap is 
perhaps the greatest civilizing agency that has been dis- 
covered, or invented. Since Chevreul’s time the demand 
for it has increased so greatly that, years ago, the supply 
of these acids from the abattoirs became insufficient to 
meet the demand, and the world has been ransacked for 
new sources of them. At the present time, only the coarser 
varieties of soap are made from abattoir acids, while all 
the finer kinds for the toilet, are made from vegetable fats 
or oils (palm, olive, cottonseed, etc.). 

As for glycerin, it was for some time a drug on the 
market until, in 1846, Sobrero discovered the explosive 
qualities of nitroglycerin, and in sixteen years later (1862) 


The Eighteenth Century 245 


Nobel devised a means of controlling its dangerous quali- 
ties. Since then, the demand for it also, has been con- 
stantly in excess of the easily available supply. 

Chevreul lived to the great age of 103 years, and wit- 
nessed the tremendous growth of these two fundamental 
industries resulting from his investigations. Many honors 
came to him before he retired. He was of course a member 
of the French Academy, and the Royal Society of London. 
On the occasion of his one hundredth birthday, he received 
the degree of LL.D. from Harvard. A beautiful monu- 
ment was erected in 1893 to his memory at Angers, the 
place of his birth; and a fine statue of him stands in the 
Museum of Natural History in Paris. 


ARAGO (1786-1853) 


ASTRONOMY 


DOMINIQUE FRANCOIS ARAGO lived in the little town of 
Estagel, in southern France, and at the age of seventeen 
matriculated at the Ecole Polytechnique in Paris, where he 
exhibited such unusual mathematical ability that he was 
offered, in 1805, the position of secretary to the Bureau of 
Longitudes, and two years later was directed to complete 
the measurement of the are of the meridian, which had 
been commenced by Delambre and Méchain. The unfin- 
ished part extended from the vicinity of Barcelona, Spain, 
due south, to the little island of Iviza, in the Mediter- 
ranean, the most southerly of the Balearic group, where it 
terminated. Establishing himself on the summit of a lofty 
mountain near the Spanish coast, he was able to maintain 
communication by signals across the 175 miles of water, 
with his collaborators on the island, and thus to carry on 
successfully the necessary observations. But before these 
were completed, war broke out between France and Spain, 
and Arago, because of his signaling operations, was charged 
by the ignorant local authorities with being a spy. How- 
ever, he managed to escape to the island of Majorca—the 
largest of the Balearic group, where he voluntarily sur- 


246 Beacon Laghts of Science 


rendered himself to arrest and imprisonment, pending con- 
sideration of his case by the central Spanish authorities. 
He was finally released, on promise to go direct to the city 
of Algiers, on the north African coast. On arrival there, 
he took a French vessel for Marseilles, which had the mis- 
fortune to be captured by a Spanish cruiser, whereupon 
Arago was sent to prison at Palamos. Again, after a time, 
he was released, and sailed once more for Marseilles. But 
almost as he was entering the port, a tempest arose that 
drove the ship back across the Mediterranean, to Bougia 
on the African coast. From there he made his way by land 
to Algiers, where he was compelled to wait nearly six 
months before he could secure passage to France. This 
was finally obtained, and in July, 1809, he at last landed 
in France. As a reward for his sufferings, the Paris Acad- 
emy of Sciences elected him to membership, a most signal 
honor, as he was then only in his 23rd year. He was also 
simultaneously appointed professor of analytical geometry 
and geodesy, at the Ecole Polytechnique. 

From this date onward, his attention was largely devoted 
to astronomy, magnetism, galvanism and the polarization 
of light, all but the first being new and budding branches 
of science. He became a tireless investigator of phenomena, 
and a brilliant lecturer, and made a number of discoveries 
of secondary importance, and one, in magnetism, of major 
value. Having heard of the discovery by Oerstead of the 
deflection of the magnetic needle, when surrounded by a 
eoil of wire carrying an electrical current, he carried the 
investigation further, by showing that the same effect could 
be produced in an unmagnetized bar of soft iron or steel, 
and to a less degree, but definitely, when a bar of copper, 
carrying no electrical current, was rotated around the 
magnet. For this discovery he obtained the Copley medal, 
and several university honors in England and Scotland, 
and was elected permanent secretary of the French Acad- 
emy, and director of the observatory at Paris, positions 
which he retained until his death. 

Arago took a prominent part in political affairs in 
France, during the disturbed period of the Revolution, and 


The Eighteenth Century Q47 


the years that followed. He opposed the election of Louis 
Napoleon to the Presidency, and refused to take the oath 
of allegiance after the coup d’état of 1851. However, in 
recognition of his great services to science, and the State, 
and in admiration of his independence of spirit, and lofty 
personal character as a citizen, the Emperor had the good 
sense to excuse him from the obligation. 


FRAUNHOFER (1787-1826) 


PHYSICS 


JOSEPH FRAUNHOFER was a native of Straubing, in 
Bavaria; and after receiving a good education in funda- 
mentals, was apprenticed in his twelfth year to a glass 
eutter at Munich, where he learned the trade thoroughly. 
Being diligent and capable, he rose quickly, and by the 
time he was of age had attained the status of a working 
optician in a large glass-making establishment, of which, 
in 1819, he became the operating head, and principal owner. 
Here he not only made money, but acquired a high reputa- 
tion for the excellence of the lenses, mirrors, prisms, and 
other scientific optical articles produced. To attain this 
end he had perfected himself in mathematics and physics, 
and had invented several machines and processes for turn- 
ing out high quality articles in his line. 

All this led up to more or less experimentation in his 
own laboratory, on the phenomena of light, and to his dis- 
covery in 1814, of the dark lines in the spectrum of the 
sunlight, which have ever since been known as the Fraun- 
hofer lines. This discovery constituted the foundation and 
beginning of the science of spectroscopy. In 1821, using a 
diffraction grating, of which he was the maker, he was able 
to measure accurately the wave length of light. These two 
very important additions to the stock of knowledge, ren- 
dered Fraunhofer’s name celebrated throughout the scien- 
tifie world. He became a member of the Munich Academy 
of Science in 1817, and in 1822 conservator of its physical 
cabinet. An unfortunate accident led to his death at the 
age of 39 years, when he was in his prime. 


248 Beacon Lights of Science 


It is true that the dark lines in the solar spectrum were 
noted by Wollaston in 1802, but he did not connect the ob- 
servation with its cause, as Fraunhofer did. The latter 
gave the names of the letters to these lines, as found in the 
solar spectrum. He then studied the spectra of stars, and 
of various flames, and observing that the line ‘‘D’’ ap- 
peared in the spectrum of all flames that he tested, he be- 
gan to search for the cause, and ultimately demonstrated 
that it was due to the metal sodium, which, being present 
almost everywhere, and at all times, in the form of sodium 
chloride (common. table salt), is to be found in almost all 
ordinary eases of flame. Thus the ‘‘D”’’ line in the solar 
spectrum indicated the presence of that element in the sun. 

With this new key, it was not long before other elements 
were shown to be present in the sun, the stars and the 
nebulae; and thus at one leap it became clear that the ma- 
terial of the external universe, was identical with those 
forms of matter that by then were being detected and iso- 
lated from the substance of the earth. Fraunhofer’s dis- 
covery was therefore epoch making, and one of the most 
wonderful in its results that are to date to the credit of 
the developing human intelligence. 


OHM (1787-1854) 


ELECTRICITY 


Grora Stmon OHM was born, and received his early edu- 
cation, at Erlangen in Bavaria; and having natural ability 
in mathematics and physics, he taught these subjects in 
various small schools, until, in 1817, he was appointed to 
a professorship in the University of Cologne. Here he be- 
came interested in what was then known as galvanism, and 
the growing electrical revelations of his time, and in 1826, 
when he resigned his professorship, he published his great 
paper, under the title of ‘‘Bestimmung des Gesetzes nach 
welchem Metalle die Contakt-electricita Leiten, ete.,’’ which 
gained him immortality among scientists. His law, therein 
set forth, which underlies all electrical theory and measure- 
ment, is substantially as follows: 


The Exghteenth Century 249 


‘“‘The capacity of any metallic conductor to transmit 
the electrical current varies directly as its length and in- 
versely as its cross-section; and is different for different 
metals, and for the same metal at different temperatures.’’ 

This transmission capacity unit is called the ‘‘Re- 
sistance.’’ Hor each substance employed in any branch of 
the electrical science, as for instance the filament of an 
incandescent light globe, or the heating coil of a toaster, 
its resistance to the passage of a current of an agreed stand- 
ard strength, has been accurately determined, and is now 
expressed, by international agreement, as so many ‘‘ohms.”’ 
Certain metals and metallic alloys (silver and copper for 
instance) transport the current with extreme rapidity and 
ease, also some non-metallics. Other metals (as tungsten), 
and most non-metallic substances (as mica, porcelain, ete.), 
are very poor conductors, or absolute non-conductors. 
When therefore any of these latter are interposed in an 
electrical current, they resist, or delay its passage. If, 
however, the resistance is only partial, the substance be- 
comes incandescent, with the production of light and heat. 
Ohm’s investigations on the conductive capacity of the 
metals enabled him to formulate the law which is now at 
the foundation of the art of electrical engineering. The 
adoption of his name to express the unit of electrical re- 
sistance will perpetuate his memory honorably through the 
centuries to come. 

The resistance of a conductor to the passage of the elec- 
trical current varies with the temperature, becoming less 
as the latter increases. Lead, for example, is rated as a 
poor conductor, but will pass a current of moderate quan- 
tity (amperage) if there is enough push (voltage) behind 
it. But its resistance causes a rise of temperature, and if 
the push continues to increase, its melting point will ulti- 
mately be reached. A strip of lead therefore, or of some 
other metal or alloy of low fusibility and indifferent con- 
ductivity, if interposed in a copper circuit, will melt and 
break the circuit if, for instance, a bolt of lightning reaches 
the copper wire, and attempts to travel on it to the deli- 
eate machinery at its end. Such arresters are a part of 


250 Beacon Lights of Science 


all electrical installations for protective purposes, and are 
popularly known as fuses. 


FRESNEL (1788-1827) 


PHYSICS 


AUGUSTIN JEAN FRESNEL was a resident of Broglie, in 
northern France, was educated at the Ecole Polytechnique 
at Caen, and at the Ecole des Ponts et Chaussées; and upon 
eraduation entered the service of the government, as an 
engineer. For political reasons, he lost his position when 
Napoleon returned from Elbe, but returned to it after the 
Second Restoration, in 1815. During his enforced idleness, 
he devoted his time to the study of the phenomena of light, 
and, in ignorance of the work of Young, the English 
physicist, on the same and allied subjects, demonstrated the 
error of the corpuscular theory, and proposed as a substi- 
tute the undulatory theory, which is today regarded as the 
eorrect explanation. His crowning experiment in demon- 
stration was with two mirrors disposed—with respect to 
each other—at an angle of nearly 180 degrees. On these, 
two beams of light were cast, and at such an angle that 
each was reflected to the point upon which the other was 
east, producing alternate light and dark bands or fringes, 
caused by the interference of the waves with each other. 

He served for several years as a member of the govern- 
ment Lighthouse Board, in which position his extensive 
knowledge of optical phenomena enabled him to improve 
the coast light system greatly. 

So far as can be gathered from what remains of their 
writings, the ancients do not seem to have developed any 
theory of the nature of light, though they clearly under- 
stood that its rays were propagated in straight lines, that 
they would be reflected in definite directions from the sur- 
face of a mirror, and could be collected to a focus by such 
lenses as they were able to construct out of transparent nat- 
ural material, or from glass after its manufacture became 
known, Curiously enough, among the Greek philosophers 


The Eighteenth Century 251 


—with the exception of Aristotle and his school—the idea 
seems to have been strongly held that vision was a purely 
mental phenomenon, and that the rays which produced it 
proceeded from the eye to the object seen, instead of from 
the object to the eye. 

Nor does it appear that any explanatory theory was ad- 
vaneed during the Middle Ages, though Kepler correctly 
described the principles of the telescope, and made some 
excellent studies in colors, while Maurolyeus some time 
previously showed that the images formed on the retina 
of the eye are inverted. 

By the time of Newton the science of optics had become 
well advanced through the labors of DeDominis, Snell, 
Descartes, Fermat, Barrow, Mariotte, Boyle and others, 
and feeling it incumbent on himself to offer some explana- 
tion of the phenomenon, that great mathematician ad- 
vanced his corpuscular theory. On account of his high 
reputation it was given immediate acceptance. According 
to it, light was due to the emission of streams of minute 
particles of matter from its source. But the difficulties 
encountered in explaining refraction by this theory were 
80 insuperable that, before he died, much controversy over 
it had arisen, and the scientists of the day were already 
looking for a better explanation. It remained for Hooke 
and Huygens, the first by a lucky guess, and the second 
after deep study, to originate in outline the undulatory 
theory, which was demonstrated experimentally by Young 
and Fresnel. When their results were published, doubts 
as to the ability of the new explanation to account satis- 
factorily for all known optical phenomena passed away, 
and the corpuscular hypothesis was relegated to the limbo 
of discredited ones. 


DAGUERRE (1789-1851) 


PHOTOGRAPHY 


Louis JAcques Manp& DAGUERRE was a native of Cor- 
meilles, in northern France, and was by occupation a scene 


Q52 Beacon Lights of Scrence 


painter, and a very successful one; for to him is ascribed 
the invention of that particular variety of spectacular de- 
lineation known as the diorama, which had a remarkable 
vogue in its day. From productions in this branch of art, 
where the contrasting effects of lights and shadows had so 
much to do with the impression made on the spectator, he 
sradually became interested in the phenomena of light. 
Entering into a correspondence with a certain Joseph 
Nicéphore Niépee, a French inventor of note, who had been 
experimenting in the same direction for a number of years, 
and who had considerable empirical knowledge of chem- 
istry, the two finally perfected their discovery of the art 
of photography, and announced it in 1839. Its value was 
immediately recognized, and Daguerre was made a mem- 
ber of the Legion of Honor, and voted a pension of 6000 
franes ($1500). 

His process was as follows: A copper plate was first 
coated with silver (by electric deposition), and then highly 
polished. It was next exposed to the vapors of iodine, fol- 
lowed by those of bromine, resulting in the production of 
a film of silver iodide and bromide. This is the cause of 
the iridescence on the plate, which all who have seen a 
dauguerreotype will recall. This preparatory work was, of 
course, done in a dark room. After exposure in the cam- 
era, the plate was subjected to the action of the vapor of 
mereury, whereupon a film of the metal was deposited on 
those parts of the plate which had been chemically affected 
by the action of the light, but not on the other parts. The 
silver film on the unaffected parts was then dissolved and 
washed away, by immersing the plate in a solution of hypo- 
sulphite of soda. Lastly, the picture was fixed and intensi- 
fied, by flowing over the surface a solution of hypo and 
chloride of gold, and applying heat gently, until all mois- 
ture had disappeared. The effect of this last step was to 
deposit on the mercury a thin film of gold. The daguerre- 
otype is therefore really a work of high art, and as such a 
great credit to its inventor. But it remained for others, 
and notably Dr. John Draper of New York, to so simplify 
the process, that it became a practicable art. And, of 


The Eighteenth Century 253 


course, during the years that have since elapsed, it has 
been further developed to a marvelous degree, and in direc- 
tions never contemplated even by Draper and his contem- 
poraries. 


FARADAY (1791-1867) 


ELECTRICITY 


MicHarn, Farapay, the son of a blacksmith, was born in 
London of Irish parentage. At an early age he was ap- 
prenticed into the book-binding trade, but having an in- 
quiring mind, he attended the lectures of Sir Humphry 
Davy in 1812, and devoted much of his leisure time to ex- 
periments in chemistry and electricity, with apparatus of 
his own manufacture. At the close of the Davy course, 
young Faraday ventured to send to him the notes he had 
made during their delivery, together with a modest expres- 
sion of his desire to secure employment, in some intellectual 
capacity. Davy was so impressed, that he at once took 
him on as a general assistant at the Royal Institution; and 
later, finding his intellect a keen one, and his desire to 
learn strenuous, he advanced him to the post of his per- 
sonal assistant and amanuensis, and explained his plans for 
making some experiments which ultimately concluded with 
the liquefaction of certain gases under pressure. In the 
construction of the apparatus required, and in its use, 
Faraday showed such ingenuity and ability, and was so 
highly commended by his generous patron, that in 1824 
he was elected a member of the Royal Society, and a year 
afterward was appointed a director of the Royal Institu- 
tion, where later, upon the untimely death of Davy, he suc- 
ceeded to his post as professor of chemistry, which in those 
days included the young but very lusty science of elec- 
tricity. In 1835 he was granted a life pension of £1500, 
and a home in Hampton Court for his residence and lab- 
oratory, and in the following year he became the scientific 
adviser (or, as we should call it, the consulting engineer) 


Q54 Beacon Lights of Science 


to Trinity House, a government organization, charged 
mainly with the erection and maintenance of lighthouses 
on the dangerous coasts of the British Isles. 

Faraday’s original discoveries and inventions were nu- 
merous and highly valuable. Most of them were in the 
domain of electricity and magnetism. All have been of 
great importance in the development of those sciences, but 
none was epochal. Thus, he was the discoverer in 1831 of 
electromagnetic induction, or the phenomenon by which a 
body having magnetic or electric properties calls forth 
similar capacities in a neighboring body without direct 
contact. In 1845, he demonstrated the ability of a strong 
magnetic field to rotate the plane of vibration of a polar- 
ized beam of light. To him we owe the useful terms 
‘‘anode’’ and ‘‘cathode,’’ and the phrase ‘‘lines of force,”’ 
which he employed in his theory of the phenomena of 
electrostatic and electromagnetic induction. His studies and 
investigation of dia and para magnetism were of the 
greatest importance, leading him to the conclusion (now 
fully accepted), that all varieties of matter are influenced 
aS universally—either attracted or repelled—by the mag- 
netic force, as by the force of gravitation, yet not invari- 
ably, or even usually, to the same degree. 

He was at once a brilliant as well as a thorough investi- 
gator, and at the same time, gifted with an imagination 
which inclined him to look beyond the immediate effects 
revealed by his experiments, and draw inferences, which in 
many cases were prophetic, but in some have not been 
realized. 

He was a deeply religious man, belonging to a sect known 
as the Sandemanians or Glassites, which was founded about 
1730 by a Scotch clergyman named John Glas, and carried 
on after his death by his son-in-law Robert Sandeman. 
It has long since disappeared. Its tenets, while in every 
way worthy, could only be held and practiced by individ- 
uals of an unusual temperament and aspect on life, and the 
fact that Faraday remained until his death an earnest 
believer in and practicer of them, reveals a phase of his 
character which probably had its influence in leading to 


The Exghteenth Century 255 


some of the few conclusions which he made, but which have 
not been realized. 

Towards the end of his long and most honorable life, his 
powers of mind began to fail, but fortunately he was 
granted his release before their decay became painful to 
his intimates. He was the author of numerous scientific 
monographs, and the complete and accurate record of his 
laboratory work as given in those published between 1835 
and 1859, under the title of ‘‘ Experimental Researches in 
Electricity’’ furnished a basis for the mathematical and 
theoretical conclusions on the subject of light, which have 
made forever famous the name of James Clerke-Maxwell. 

In recognition of his numerous and important contri- 
butions to the advance of the science of electricity, particu- 
larly in the matter of electrical condensation, his name, 
shortened to ‘‘farad,’’ has been internationally adopted to 
represent the ‘‘ practical unit of electrical capacity,’’ which 
may be defined as the capacity of a condenser whose poten- 
tial is one volt, when charged by one coulomb. The term 
is most frequently used in the form of the ‘‘microfarad,’’ 
which is the one-millionth part of a farad. 


VON BAER (1792-1876) 


EMBRYOLOGY 


Karu ERNST VON BAER was a native of Esthonia, one of 
the western provinces of old Russia occupying a part of the 
southern coast of the gulf of Finland. He was educated 
at the University of Dorpat for the medical profession, and 
after graduating studied anatomy at Wurtzburg. In 1817 
he became an instructor at the University of Koénigsberg 
and later professor of zoology, and director of its Anatomi- 
cal Institute. In 1834 he moved to St. Petersburg, became 
connected with the Academy there, and remained in that 
city during the remainder of his life. 

He is recognized as one of the founders of the modern 
science of embryology, and was the discoverer of what is 
known as Baer’s Law, as follows: 


256 Beacon Lights of Science 


‘The evolution of an individual of any animal form, is 
determined by two conditions: first, by a continuous per- 
fecting of the animal body by means of an increasing dif- 
ferentiation—histological and morphological—or an in- 
creasing number and diversity of tissues and organic 
forms; and second, and at the same time, by the continuous 
transition from a more general form of the type, to one 
more specific.’’ 

Wilhelm His of Germany was the first writer of note on 
this subject. His book, which is a classic, appeared in 1885, 
and embodied all that had been discovered on its subject to 
that date, in all respects confirming the law that Baer had 
announced. Since then much new information has been 
cathered although, as subjects for investigation are natur- 
ally much more difficult to obtain than those of adults, the 
additions to knowledge of human embryonic life accumulate 
slowly. Much more is known of that phase in animals and 
in vegetable life. 

The human period of parturition varies a few days either 
way from 270, or say 3814 weeks. The first stage, which 
has a leneth of about two weeks, is that of the ovum 
or egg. Of it almost nothing is known except of the last 
three or four days. At its termination the new organism 
has a length of not over one-tenth of an inch, and consists 
of a collection of minute cells enclosed in a bladder-like 
covering or skin. The second stage embraces the next 
three weeks. During it a length of nearly a half inch is 
attained, and most of the principal organs come into exist- 
ence, and may be located. This is called the embryonic 
period, and is the one which displays signs of the animal 
ancestry of man, such as the gill clefts and arches, the 
limb buds, and the beginnings of the vertebral column or 
back bone. Before its termination the brain has grown 
so rapidly that the head is as large as all the rest of the 
body, a feature characteristic of the human embryo only. 
Also the gill clefts and arches have almost disappeared, 
the arms have grown faster relatively than the legs, and 
the general outlines of the skeleton can be traced in lines of 
cartilage, though no bones have yet appeared. 


The Eighteenth Century 257 


The organism now passes into the third and final stage, 
called that of the foetus. In its early weeks the sex char- 
acteristics are determined. Before that, their germ was 
a part of what is called the Wolffian body, which up to 
about the seventh week performs the functions of an excre- 
tory organ. All but a central part of this now disappears. 
The remainder is ealled the sexual gland. If the child is 
to be a boy, parts of it degenerate and the balance becomes 
the internal male organs. If a girl, the male part degen- 
erates and those remaining become the internal female 
organs. Hair begins to appear on the scalp during the 
fourth month, and the cartilage of the skeleton here and 
there is slowly changing into bone. At the beginning of this 
stage a weight of about five ounces, and a length of about 
six inches has been attained, and the human features are 
discernible on the face. In the following month these meas- 
urements are nearly doubled. Hair is now well developed, 
and also the nails on hands and feet. The sixth months’ 
child weighs a good pound and is eleven to twelve inches 
long. During the seventh weight increases to three or four 
pounds, and the length to thirteen to fifteen inches. If 
birth now occurs life is possible, for all the organs are in 
existence and capable of functioning, though but feebly. 
When the full period is reached the weight is normally 
from five to nine pounds, and the length from seventeen to 
twenty-one inches, boys weighing on an average about 
twelve ounces more than girls, and being four to five inches 
longer. 

At the normal time of birth the bony skeleton is very 
incomplete, being still largely in the condition of cartilage. 
In fact the only bones entirely hardened at that time are 
those small ones df the internal ear. To this curious fact 
is due the extreme sensitiveness of infants to sound. Their 
earliest impressions of the astonishing world into which 
they have come reach them mainly through the sense of 
hearing. Long before the eye has learned to interpret the 
meaning of the inverted image it presents to the brain, the 
voice of the mother has become familiar, and is recognized 
as a symbol of protection. 


258 Beacon Laghts of Scvence 


LOBATCHEVSKY (1793-1856) 


MATHEMATICS 


NIcoLAl IvANOvITCH LOBATCHEYSKY, the son of a peasant, 
was born at Nijni Novgorod in Russia. He received (or 
acquired), in spite of the handicap of poverty, a good edu- 
cation in the fundamentals, and having unusual mathe- 
matical ability became one of the noted geometers of his 
time. In 1816 he was appointed professor of this science in 
the University of Kazan, a position which he retained with 
sreat credit during the balance of his life. 

His major achievement—aside from being a remarkably 
successful instructor, and the producer of numerous very 
valuable monographs on mathematical subjects—was the 
discovery and elaboration in a volume published in 1830,— 
of what is known as the Non-Euclidean system of geometry, 
that is, one not based upon the Euclidean postulate of par- 
allel lines. In this enlargement of the field of the science 
he was, to a certain extent, anticipated by the investiga- 
tions of the brilliant Hungarian mathematician, Janos 
Bolyai, but to Lobatchevsky properly belongs the credit of 
having developed the new system and bringing its advan- 
tages into practical use. 

Geometry, the science of form, owes its beginnings prob- 
ably to the necessities of the rural inhabitants of the valley 
of the Nile (and doubtless also those of the Tigris and 
Euphrates) to have their boundary lines re-set after each 
annual inundation; in other words, with the art of land 
surveying. This called for the ability to calculate correctly 
the areas of irregularly shaped plots of ground that were 
bounded by straight or curved lines, or both. _Up to the 
early years of the 19th century, among the fundamentals 
of the science were two axioms, or apparently self-evident 
truths, which had been accepted along with the others with- 
out question. These were as follows: 

(A) Two parallel lines cannot completely include a 
space between them; and 

(B) If a straight line meets two straight lines in such 


The Eighteenth Century 259 


a way as to make the two interior angles on the same side 
of it together less than two right angles, the two straight 
lines, if produced, will at length meet on that side on which 
are the angles whose sum is less than two right angles. 

Both Legendre and Gauss, as well as a number of other 
noted mathematicians endeavored to show the dependence 
of these two propositions upon those preceding them. 
Lobatchevsky showed that they applied only in plane geom- 
etry, but not in spherical. For, on a sphere, it is evident 
that two parallels of latitude do really include a space 
between them, to which has been given the name of a zone; 
and it is equally clear that the angles made with two such 
parallels by a meridian crossing them perpendicularly, do 
not, on either side, amount together to the sum of two right 
angles; and yet that the parallels, no matter how large the 
sphere, will never meet. 


WEBER (1795-1878) 


PHYSIOLOGY 


ERNEST HEINRICH WEBER was a native of Witteberg, 
Germany, and after a thorough grounding in medicine and 
anatomy at the university of that city, and at Leipsic, was 
appointed professor of comparative anatomy, in 1818, at 
the latter, was advanced to the chair of human anatomy in 
1821, and to that of physiology in 1840. In his investiga- 
tions, he gradually specialized on the physiology of the 
organs of sense, which naturally in time led him into the 
domain of psychology, and resulted in his announcement of 
a generalization of great importance in psycho-physics, 
which is known as Weber’s law. This has been exhaustively 
tested by contemporary and subsequent investigation, and 
is fully accepted at the present time. 

By a direct experiment upon a living animal, Weber was 
the first anatomist to discover that the pneumogastric 
nerve, the longest and most widely distributed of those 
originating directly in the brain, extending from there 
downward through the neck and chest to the upper part 


260 Beacon Lights of Science 


of the abdomen, exercised an inhibitory or controlling ac- 
tion on the heart, and the respiratory organs, in effect, 
playing a part in connection with their movements similar 
to that of the governor to a steam engine. If a certain 
branch of that nerve is stimulated, either naturally by 
vigorous muscular action, or artificially by drugs, the 
pulsations of the heart are increased in number. If an- 
other branch is stimulated in either way, the heart throbs 
decrease in number. Weber’s law is the formula express- 
ing the relation of sensation to intensity of stimulus; in 
effect stating, ‘‘that the ratio of the increment of stimulus, 
necessary to give a noticeably different sensation to the orig- 
inal stimulus, is constant.’’ The validity of this conclu- 
sion was confirmed by Fechner, who extended its range to 
all cases of sense perception; and Wundt gives a résumé 
of its applicability as follows: 

‘‘The law has its most satisfactory application, and its 
widest range, in noise intensities. It has a less extended 
application to the modalities of vision, touch, taste and 
smell, while its validities in temperature, and organic sen- 
sation, are as yet uncertain.’’ 

The phenomenon then lies in the domain of psychophys- 
ics, that branch of science dealing with the inter-relations 
of mind and body, which, during recent years, has increas- 
inely attracted the attention of investigators. As our 
knowledge of it, and of its reactions grows, its conclusions 
are slowly but steadily displacing those of metaphysies, 
which is fading into the status of a pseudo science, as 
astrology and alchemy have. For many years after Coper- 
nicus announced the approximately correct theory of the 
Cosmos, and Dalton the correct theory of the chemical ele- 
ments, both of those pre-scientific cults continued to influ- 
ence the minds and actions of all but the most advanced in- 
tellects. So metaphysical theories still have their votaries. 
But with the establishment, on the basis of observed and 
demonstrated facts, of Weber’s conclusions, the science of 
psycho-physies is taking its place. 

Weber’s law means, in effect, that stimuli reaching the 
brain through the sense organs (vision, hearing, taste, 


The Eighteenth Century 261 


touch and smell) exert an immediate influence on the ac- 
tion of the heart and lungs, and reflectively result in the 
expression of what we eall ‘‘emotions.’’ These display 
themselves in various ways, sometimes causing death or 
insanity, or, as we say, breaking the heart. And further, 
of those organs, that of hearing, which conveys to the mind 
speech, music, and all other varieties of sound or noise, is 
by far the most responsive to such stimuli. 


SADI-CARNOT (1796-1832) 


PHYSICS 


NicHOLAS LEONARD SADI-CARNOT, the son of a celebrated 
French statesman, strategist and scientist, was born at 
Paris, received his technical education at the Eeole Poly- 
technique, and served in the corps of army engineers until 
his resignation in 1828. Years before he had become deeply 
interested in the performances of the steam engine, as con- 
structed in 1782 by James Watt, and the phenomena of 
heat. In his day this force was still regarded as a form of 
matter, and was called ‘‘caloric.’’ Carnot supported that 
view in his work entitled, ‘‘Thoughts Upon the Motive 
Power of Fire and the Proper Machine for Utilizing its 
Power,’’ and maintained it with so much ability and logic, 
that his exposition, with a few changes in terminology, was 
eapable of adaptation to the dynamical theory of heat 
shortly thereafter demonstrated, and accepted by himself 
before his death. For in it he showed, that the amount of 
work possible to be done by any heat engine, depends upon 
the quantity of heat transferred, and the difference in tem- 
perature between the source of heat, and that of the appli- 
ance in which its expansion and loss of temperature occurs, 
as in the cylinder of the steam engine. Which, in effect, 
was the second law of thermodynamies as later enunciated 
by Clausius, in 1850. It is plain from the language of his 
monograph mentioned, that Carnot had grasped the fun- 
damental idea of the Conservation of Energy, for he stated 
therein ‘‘that motive power is, in quantity, invariable in 


262 Beacon Lights of Scrence 


nature, and can neither be produced nor destroyed.’’ To 
demonstrate this principle he constructed what he called 
a reversible engine, where the amount of heat (caloric) 
applied, and the amount of motive power (energy) real- 
ized, could be observed and investigated under ideal con- 
ditions. In his early death at the age of 36, the world 
lost a clear and thorough thinker. 

The true nature of heat as a form of motion began to 
be correctly understood when Rumford raised the tempera- 
ture of a block of iron by drilling a hole into it with a steel 
bit. Following this demonstration, it was shown that two 
pieces of ice rubbed together would result in the melting 
of both, and that if a paddle was turned rapidly enough 
in a vessel of water, and long enough, the water could be 
brought to the boiling point. In all these cases the rise in 
temperature results from friction, by which the molecules 
of the substances affected are caused to vibrate more rap- 
idly among themselves than they do under normal condi- 
tions. Ice is cold to the touch because, when taken into 
the hand, the normal vibrations in the flesh which produce 
the natural body temperature of about 98° Fahrenheit, are 
slowed down by the transference of part of that rate of 
vibration to the ice, the temperature of which at once be- 
gins to rise above its normal of 32° Fahrenheit. Heat is 
then said to pass from the body to the ice, but in reality 
only motion passes, and in the transit the work performed 
is that of the melting of the ice, consisting of its change 
from the condition of a solid to that of a liquid. 

In interplanetary and interstellar space, where matter 
is believed to be non-existent, temperature also does not 
exist. The absolute zero has been calculated at minus 
273° on the Centigrade scale, and minus 491° on the 
Fahrenheit. A close approach has been made to it when 
the elementary gas helium was liquefied in 1898 at the tem- 
perature of minus 250° Centigrade and the gas hydrogen 
solidified at minus 257° C. At the absolute zero it is be- 
lieved that all molecular motion ceases, and simultaneously 
all capability of chemical action. 


The Evghteenth Century 263 


LYELL (1797-1875) 


GEOLOGY 


CHARLES LYELL was born at Kinnordy in Seotland. His 
early education was received at Midhurst in the south of 
England, after which he entered Oxford, receiving his de- 
eree of M.A. in 1821. He then enrolled himself as a stu- 
dent in law and was admitted to practice in 1824. During 
these seven student years he took an active interest in the 
meetings of the Geological and the Linnean Societies, and 
contributed a number of ereditable articles on science to 
the technical periodicals of the time. In 1826 he was elected 
a member of the Royal Society. Two years later, in com- 
pany with Sir Roderick Murchison, he traveled in various 
parts of Europe, and in Sicily became deeply interested in 
the many evidences of the slow but steady elevation of that 
island from the sea. These led him to the belief that 
geological changes are not catastrophic phenomena as was 
the general opinion of the day, but gradual movements, 
persisting through long ages. Finding ample confirmation 
of this theory wherever he went, and particularly in Ger- 
many, England and Scotland, where he made exhaustive 
study of the Tertiary formation and its fossils, he began 
the writing of his great work entitled ‘‘Principles of Geol- 
ogy,’ the first volume of which appeared in 1830, and the 
other two in 1832 and 1833. This production proved to 
be epochal in its effects. Previous to its issue the catas- 
trophic theory advocated by the German geologist Werner 
had been accepted everywhere, partly because of the 
great ability with which it had been presented, but mainly 
because it was not antagonistic to the orthodox concep- 
tions of the creation of the world. Ags Lyell’s views could 
not be squared with the latter, his books precipitated as 
violent a controversy between the old and the new schools 
of thought, as did those of Darwin thirty-five years later. 
The demand for them passed all expectation, and before 
a decade had elapsed their conclusions were accepted 
everywhere outside of the most conservative circles. It 


264 Beacon Lights of Science 


should be here stated that Lyell did not claim originality 
for his beliefs. On the contrary, and in the most explicit 
terms he called attention to the fact that Hutton, nearly 
a half century previously, had been the first to advance 
the doctrine in his ‘‘Theory of the Earth,’’ which ap- 
peared in 1795, but had attracted practically no attention 
because of the comparative social obscurity of.its author. 

Lyell is, however, popularly regarded as the founder of 
the modern science of geology. And because of his exten- 
sive travels, and the wide opportunities they afforded to 
present examples of the views he advocated, he was able 
to cite such abundant proofs, and to give them in language 
so simple and interesting, that denial of their verity in 
general could not logically be maintained. At the present 
time these, under the unwieldy name of ‘‘uniformitarian- 
ism,’’ are everywhere accepted; though naturally, in many 
matters of detail, his conclusions have been modified, or 
even supplanted, as a result of the accumulation of new 
and more precise information as the science, and its allied 
branch paleontology, expanded. 

When Darwin came upon the stage and enunciated his 
theories on Evolution, Lyell, then an old man, and the 
recipient of many honors from scientific societies all over 
the world, became one of his most enthusiastic supporters. 
He was knighted in 1848, and later received a baronetcy. 
Twice he came to America, in 1841 and 1846, and delivered 
lectures on geology which drew large and appreciative audi- 
ences. His mortal remains rest in Westminster. 


HENRY (1799-1878) 


ELECTRICITY 


JOSEPH HENRY, an American physicist, was born at Al- 
bany, in the state of New York, and received his education 
at the Academy of that city where, at the age of twenty- 
seven, he became professor of mathematics. In 1832 he was 
appointed to the chair of physics at Princeton University, 
form which post he went in 1846, to become Secretary of 


The Eighteenth Century 265 


the Smithsonian Institute at Washington, a position which 
he held during the remainder of his active life. In 1849 he 
was elected president of the American Association for the 
Advancement of Science, and in 1858 to the same position 
by the members of the National Academy of Sciences. 
Upon the establishment of the Lighthouse Board in 1852, 
he became a member, and in 1871 its chief. 

Throughout his whole professional career he was pre- 
eminently an experimenter of the highest order, specializ- 
ing in the domain of electricity which, at the time, was 
attracting the attention of investigators throughout the edu- 
eated world, to a greater extent than any other depart- 
ment of science. He is properly to be credited with the 
invention of a number of devices for enabling the electrical 
current to perform work, by far the most important of 
which was his installation of a mile or more of fine copper 
wire, between his residence and his laboratory at Princeton, 
which employed the earth for the return circuit, a com- 
pletely new idea then. This construction, provided at one 
end with the equivalent of the telegrapher’s key, and at 
the other with a crude form of the electromagnet and arma- 
ture, was arranged to ring a bell, and constituted the first 
real telegraphic system, the foundation upon which, in 
1837, Morse perfected the instrument, and invented the 
code of signals by which it became possible to transmit 
language. In other words, Henry was the first utilizer of 
the principle at the foundation of the telegraphic art, but 
Morse was the inventor of the apparatus by which it be- 
came a practical one. 

In acknowledgment of the great part his labors had to 
do with the marvelous art of telegraphy, his name (henry) 
was adopted by the International Electrical Convention as 
the unit of induction in an electrical current, when the 
induced electromotive force therein is the equivalent of 
one volt, while the inducing current varies at the rate ot 
one ampere per second. 


ay? ‘4 i, ¥ | | in ct : 4 oa . . bil ba cea 











| ees 
| Aw wt at) AY on a) 
td \ ‘v , Bs 2 My ‘ ee ; 
be SAY Ds . ny a a s} ‘ea rary hue dee a meihy Abe 
SO AEs Ga Od to Bg Ahan SN A re oe a Shaan 

















« «i ih ‘ 
S; Hy ee kane 
’ Nr, ; a ‘ : 
: i} ‘ ¥ f 
Lee bY 3 7 ive D A Piety) 
? ‘ 
i 1g Le 
“io cevar ‘i 5 } an Vi wees 
‘ ry ’ 4 
ne ee 
' ; ‘ A “ af" 


i et a wy ’ vs ry) Ui : Wi | ; * j ‘ ‘ se iV 
; f t en Tae 5 Pig a ae poe by rT a a, Wi, 


¢ Ny stat cr pane poe To Ale re eats at je en ye a lg mins 


if 


\ ‘ pdeck : a eh ue 7 
vikg ‘ ed a a 
i iC yt we whe rate arse (y 46 Sah eet AN ik oad Pets — rad 
Taha ie Cr a Mises AeA ; 4 eels 
we. ia Weis , 
L Paik Ng of ‘ ; LA es 7 4 Be ' a ents oie : 


Pe as ; ty ce Wal ig i ae Sy, ARV: sees ee a bile si “ 
bali raat awe ie ee eA rien ee ipreee 
ee fit Bite La. om 








yeasts “dae Ae aati Ai Siantan ae 
. i} REA seal = sunt. i 


qhy ua phe Py poe nh) NY Sepa eee Again urit 
¥ : i t 7 ’ Y4 a 
hit dt ¥ Fag. ett 4 A) Rt ara tga Hi 9, ga No 











VI 


THE NINETEENTH 
AND TWENTIETH CENTURIES 


Most readers are already familiar with the political history of 
this century and a quarter; however, it may be of advantage to 
summarize its salient features. 

Great Britain, despite numerous external wars, has preserved a 
large measure of domestic tranquillity and has remained the greatest 
colonizing nation in history. By the middle of the last century she 
had beeome the commercial and financial center of the world. In 
the field of science she has produced a noteworthy group, as the list 
shows. 

Germany threatened for a time to wrest away Great Britain’s com- 
mercial supremacy. Under the strong leadership of Prussia she 
attained political unity in 1870, and built up unde: a benevolent 
despotism a vigorous national life in which learning, commerce, anc 
militarism worked conjointly. But militarism got the upper hand, 
and in the disastrous World War Germany lost ground in both the 
other fields, which it will take many years to regain. 

The Napoleonic Wars of a century ago left France impoverished 
in many ways. The periods of domestic upheaval and outside wars, 
which have succeeded, have likewise seriously handicapped her scien- 
tific attainment. Yet of her small group of scientists at least six 
have been of the first rank. 

The outstanding factor in this period is the rise of the United States 
from an untried nation to a great world power. The aftermath of 
war has given this country tremendous financial and political power. 
In the fields of invention and science the contribution has been like- 
wise noteworthy—a promise of still greater things to come. 


DUMAS (1800-1864) 


CHEMISTRY 


JEAN Baptiste DumMASs was born at Alais in southern 
France. His education in fundamentals was excellent, but 
in the higher branches not so good. Nevertheless, from 
early youth he was constantly experimenting in chemistry, 
and by reading acquired a thorough knowledge of its prin- 
ciples. Family necessities compelled his apprenticeship to 
an apothecary in Geneva, Switzerland. While serving there 
he privately carried on some chemical investigations which 
came to the knowledge of De Candolle, the botanist, and 
resulted in his removal in 1823 to Paris, where he secured 
the position of tutor at the Polytechnic. This led later 
to the position of a professor at the Athenaeum, where his 
ability and charm as a lecturer soon secured his transfer 
to the university popularly knwon as the Sorbonne, and 
his election as a member of the Academy of Sciences. 

The temperament of Dumas was that of the investigator, 
and in a very short time he became known internationally 
through his research work on the atomic weights of the 
elements, on the properties of sulphuric ether, and on the 
phenomena of substitution in organic chemistry. In his 
time the question of the relative atomic weights of those 
elements then known, was a matter of first importance to 
the chemist, for Dalton had but recently (1808) published 
his theory of atomicity, and demonstrated its vital rela- 
tion in the processes of analysis. In accordance with the 
hypothesis put forward at the time by Prout, to the effect 
that all the elements were probably compounds of hydro- 
gen, which was admitted then to be highly probable; to that 
gas, the lightest substance known, was given the weight of 
1, and to all the others, as fast as determined, the higher 


269 


270 Beacon Lights of Science 


number which, by comparing their weight to that of hy- 
drogen, repeated determinations indicated they should 
have. By the early chemists these figures were preferably 
called ‘‘combining equivalents.’’ Later, as hope for un- 
doubted evidence of Prout’s idea declined, and was prac- 
tically abandoned—and by most students forgotten—it be- 
came more convenient for several reasons to adopt oxygen 
for the standard of relative equivalence. The change ac- 
cordingly was made about 1868, and has remained in force 
ever since. But, curiously enough, the knowledge acquired 
during the last ten years or so of the nature of the chemi- 
eal atom, has resulted in the revival of Prout’s hypothesis, 
and led many physicists already to the belief that before 
long it will be clearly demonstrated to be true. However, 
when and if that occurs, it will effect no change in the 
methods and results of laboratory work, and, in fact will 
be a matter of indifference to the chemist, for the new 
atom will then have become purely a physical affair, a unit 
or a collection of units of energy, with whose behavior as 
such he will have neither the desire nor the power to deal, 
for the molecule will still remain—as now—his exclusive 
field, and will continue to respond as immutably as hereto- 
fore to his manipulations. 

The compound upon which Dumas made his investiga- 
tions under the name of ‘‘sulphuric ether,’’ was the first 
of the anaesthetics, having been accidentally discovered by 
the alchemists as far back as some time in the 18th century. 
But by them neither its composition, nor a method of pro- 
ducing it with certainty, nor its properties of inducing tem- 
porary insensibility to pain, were known. They regarded it 
as a most dangerous substance, the equivalent of a deadly 
poison. It was assumed to contain sulphur in the form of 
sulphuric acid, but in the pure article neither are present. 
Its true composition was not known until early in the 
19th century. As the result of the researches of Dumas 
its properties became sufficiently understood to permit of 
its employment in long surgical operations, where nitrous 
oxide cannot be used because its effects are too transitory. 

In the early years of the science of organic chemistry, 


The Nineteenth and Twentieth Centuries 2'71 


after the existence of organic radicals had been well estab- 
lished, and after the electronegative and electropositive 
theory of Berzelius had been applied to them without suc- 
cess, Dumas was able, as the result of experiments he had 
been making on acetic acid, where he found he could sub- 
stitute chlorine for hydrogen, and still have a compound 
retaining most of the properties of the acid; to suggest, in 
1839, that a like process of substitution should be possible 
with organic radicals, provided they were first catalogued 
into types. This was the fundamental step in the cele- 
brated ‘‘theory of types,’’? which was subsequently worked 
out with perfect success, and was recognized during the 
lifetime of its originator as one of the most important ad- 
vances in the development of the science. 

After the revolution of 1848, which overthrew the gov- 
ernment of Louis Philippe, Dumas became a member of 
the Council of Education; and from 1849 until 1851 he was 
a member of the Department of Agriculture and Commerce. 
After the coup d’état in 1852, which revived the Empire 
and carried Napoleon III to the throne, he became a sena- 
tor, and a member of the Council of Public Instruction. 
During the remainder of his active life, while contributing 
frequently to the pages of scientific periodicals, he served 
the public in various capacities, and was regarded as one 
of its foremost citizens. 


WOHLER (1800-1882) 


CHEMISTRY 


FRIEDRICH WOHLER, a native of Frankfort-on-the 
Main, in Germany, was educated at the local gymnasium, 
and then studied medicine and chemistry at the universities 
of Marburg and Heidelberg. After graduation he became 
asisstant to the chemist, Berzelius, in Stockholm, Sweden. 
In 1825 he moved to Berlin, and became an instructor in 
chemistry at the newly established industrial school of that 
city. In 1836 he took the chair of chemistry at the Univer- 
sity of Gottingen, where he remained until his retirement. 


272 Beacon Lights of Science 


During the first quarter of the 19th century, the science 
of inorganic chemistry became well established. Most of 
the commoner elements had been recognized as such, the 
atomic theory of Dalton had been demonstrated beyond all 
question, Lavoisier had introduced the balance as the fun- 
damental tool of the laboratory, Berthollet had made clear 
the principle of chemical equilibrium, and Gay-Lussae the 
law of combining volumes. 

But in the domain of organic chemistry, which has to do 
with those forms of matter found in living things—plants 
an animals—the old alchemistie theory of a ‘‘vital force’’ 
as the cause of the myriad transformations constantly in 
progress in the world of life, still held sway. 

When, therefore, Wohler announced in 1828 that he had 
effected the synthesis of urea, a compound that derives its 
name because it was first found in human urine (of which 
it forms the most important and characteristic ingredient), 
the intellectual world of the day was notably startled, and 
the conservative part of it—as usual—rather shocked. 
When the discovery came to the notice of Liebig, who was 
perhaps the most widely known chemist of the time, and 
also a man wholly free from prejudice, he took it up with 
enthusiasm, and, working with Wohler, laid broad and 
deep the foundations of the science of organic chemistry 
which, since then, has become the most comprehensive 
of all the sciences, without which the industrial life of the 
present time could not have arisen. 

To Wohler also belongs the credit of discovering the first 
ease of isomerism, that is, the existence of organic sub- 
stances or compounds which have identical composition, 
and yet entirely distinct properties. Since his day many 
hundreds of such have become well known. 

In 1832, in collaboration with Liebig, they took up the 
study of a series of compounds allied to benzoic acid, an 
organic substance occurring naturally in certain gums, and 
found that they could be changed into one another, and 
that throughout these transformations a group of atoms 
consisting of carbon, oxygen and hydrogen remain un- 
changed. They called the latter the benzoyl radical. This 


The Nineteenth and Twentieth Centuries 273 


was quickly followed by the discovery—also by them—of 
the ethyl radical, which is common to alcohol and ether; of 
the cacodyle radical by Bunsen, which is possessed in com- 
mon by several compounds of arsenic; and a number of 
others, all of which, though themselves compounds, be- 
haved like single atoms of an element. Berzelius took up 
this important discovery in his enthusiastic way, and at 
once began to classify these radicals into the two groups 
of electropositive and electronegative, as he had already 
elassified the elements; and endeavored to isolate them, 
under the belief that they were really undiscovered ele- 
ments. In this he was unsuccessful, and when his electro- 
chemical theory was abandoned it was for a time believed, 
in the chemical world of the day, that the theory of organic 
radicals or pseudo-elements would also soon have to be 
given up. for a while Dumas’ theory of type radicals 
seemed to be capable of at least deferring the demise of 
the whole theory. Finally, the conception of valency was 
introduced into that investigation, showing the different 
ways in which the atoms could be linked together into 
these radicals. This, in the end, has explained why and 
how the molecules of different substances can be composed 
of the same number and kind of atoms, and yet possess en- 
tirely distinct properties. But in recent years it has be- 
come apparent that something yet has to be learned about 
the nature and behavior of these compounds, before the 
chemist will have complete manipulative control of them. 


MULLER (1801-1858) 


PHYSIOLOGY 


JOHANNES MULLER was a native of Coblenz in Germany, 
and was destined for the ministry, but abandoned that 
profession for medicine and physiology, obtaining his edu- 
eation at the University of Bonn, from which he graduated 
in 1822. He then pursued his studies for a time at Berlin, 
but returned in 1826 to Bonn to become at first a tutor, 
then an assistant professor, and finally, in 1830, a full 


Q74 Beacon Lights of Scrence 


professor. In 1833 he went back to Berlin, and took the 
chair of anatomy and physiology at the university there, 
a post which he retained for the remainder of his life. 

His great work, entitled ‘‘ Handbook of Human Physi- 
ology,’’ appeared in the years between 1833 and 1840, and 
is regarded as an epoch-making production in its specialty, 
as it embodies all his important discoveries. He was the 
founder of a new school of practice in his profession. To 
him physiology owes the foundation of Bell’s law, the 
principle of reflex movements, and a knowledge of the com- 
position and source of cartilage. He discovered the pro- 
nephric ducts in the kidneys, explained the nature of 
hermaphroditism, laid the foundation of the present knowl- 
edge of the embryology and the metamorphoses of the 
echinoderms, discovered the lymph hearts of the amphibi- 
ous animals, the micropyle of the eggs of fishes, and made 
clear many other theretofore obscure living structures and 
organs. 

Cartilage is a firm elastic substance of a pearly color and 
apparently uniform composition but, like all other varieties 
of bodily tissue, when examined under the microscope, is 
resolved into a dense collection of cells with a matrix of 
fine fibrous tissue, itself also cellular. In the unborn child 
the skeletal bones begin as cartilage and some, particularly 
those of the extremities, are not ossified at birth. In fact, 
the process of changing into bone is rarely complete before 
the age of puberty, and many instances have been recorded 
where it was still in progress at the age of twenty. 

All of the cartilage that exists in the body of the infant 
does not alter into bone. Some of it, wherever the joints 
occur, retain the original cartilaginous characteristics of 
flexibility and moderate elasticity, and become ligaments, 
tying the bones together at their ends. Another variety of 
this useful body substance is called the non-articular carti- 
lage, because, as in the case of the nose, it is attached to 
a bone at one end only, the other end forming the flexible 
tip of that organ; or, in the case of the ear, the external 
shell-like convolutions. 

The processes by which the soft cartilage of the child 


The Nineteenth and Twentieth Centuries 275 


changes into the hard bone of the adult, consist of the 
infiltration into it of earthy material, consisting mainly of 
the phosphates and carbonates of lime, which render the 
former flexible substance rigid. This change is continuous 
and progressive through life, so that the bones of elderly 
people become brittle and are easily broken, while in the 
infant and the youth they are so flexible that a clean frac- 
ture is almost impossible. To secure the best physical 
development, the food in youth should contain plenty of 
lime. After maturity foods containing a minimum amount 
are preferable. 

If the well cleaned bone of an adult is treated with a 
dilute mineral acid, the lime salts in it will be dissolved 
out, but the flexible cartilage throughout it will remain 
unaltered. If, however, the bone is burned, the cartilage 
will be destroyed, while the mineral constituents will re- 
main largely unaffected, so that the shape is preserved. 
But a slight blow or shock will cause a bone so treated to 
erumble into ashes. Throughout life the bones are nour- 
ished, and fractures are knitted together, by the unaltered 
cartilaginous material persisting in their structure. 


ABEL (1802-1829) 


MATHEMATICS 


NieLs HenrRIK ABEL was a native of Findde, Norway, 
and educated at the University of Christiana. After two 
years spent in study in Paris and Berlin, he was employed 
as an instructor at the school of Engineering in Christiana. 

During his brief career he became known, through his 
literary contributions to technical periodicals, as one of 
the ablest mathematicians of his day. His principal atten- 
tion was given to the theory of functions, of which he, with 
Jacobi, were the founders. An important class of these— 
the elliptical—are known as the Abelian Functions, and 
were developed by him. He was the first to demonstrate 
the impossibility of solving by the elementary processes of 
algebra, general equations of any degree higher than the 


276 Beacon Laghts of Science 


fourth. He also extended the capacity of the Binomial 
Formula, by including in its scope the cases of irrational 
and imaginary exponents. 

In mathematics a function is a quantity whose value 
depends upon the value of another quantity. Thus, when 
the statement is made that the circumference of a circle 
(called ‘‘e’’ for convenience) depends upon the length of 
its diameter (called ‘‘d’’ for the same reason), then ‘‘e’’ 
is said to be a function of ‘‘d,’’ the relationship between 
them being expressed symbolically by the Greek letter z, 
which stands for the constant figure 3.1415926, it having 
been demonstrated that invariably the product obtained by 
multiplying the length of the diameter by this figure will 
give accurately the length of the circumference. 

Abel and Jacobi studied the ellipse, just as the circle 
had been studied centuries previously, and as Legendre 
had been doing at least a quarter of a century before they 
began, as shown by his notable work published in 1828. 
But their results surpassed those of Legendre in that they 
discovered the double periodicity of elliptical functions. 
As the planets and the periodic comets, as well as all the 
satellites of the planets, revolve in elliptical orbits instead 
of circles as believed by Copernicus, the importance of un- 
derstanding all the properties of that curve—which has 
been called the circle of two centers—can readily be under- 
stood. 

An equation, as the word is employed in algebraic work, 
is a Statement made by the use of symbols instead of words, 
of a condition of equality existing only for particular val- 
ues of certain letters or symbols representing (for the time 
being) unknown quantities. For those whose numerical 
value is sought, the letters ‘‘x’’ or “‘y’’ are usually em- 
ployed. Thus, 24+-3—9 is a simple equation, because 
the statement of equality is true only if the value of 3 is 
given to the symbol ‘‘z.’’ On the other hand the state- 
ment 2-+-5=7 is a numerical statement of equality, but 
not an algebraic equation, because all the quantities are 
positive, definite and known. But if we write x+5—7 
we have the true simple algebraic equation, because the 


— 


The Nineteenth and Twentieth Centuries 277 


unknown value of ‘‘x’’ depends upon the values of the 
numbers ‘‘5’’ and ‘‘7,’’ and may be readily ascertained by 
transposing the form of the equation, thus: ==7—5, 
which is 2. 


WHEATSTONE (1802-1875) 


PHYSICS 


CHARLES WHEATSTONE lived in Gloucester, England, and 
was a maker of musical instruments, ultimately becoming 
deeply interested in, and a reliable investigator of, the sci- 
entific principles involved in their construction and use. 
He was the first to make the attempt to measure minute 
intervals of time. This he accomplished by a device which 
he called a chronoscope, of which various forms have since 
been constructed. All depend substantially upon a mirror 
mounted on a vertical or horizontal axis, and caused to 
revolve at a high rate of speed, by means of appropriate 
machinery. The problem he set out to solve was the dura- 
tion of the flash of an electric spark, which he accomplished 
with a mirror revolving at a speed of 800 turns per second. 
His results were published in 1834, in a monograph entitled 
‘‘Experiments to Measure the Velocity of Electricity.”’ 
This attracted so much attention, that he was appointed 
professor of experimental physics at King’s College in Lon- 
don. Here he continued his researches, and in 1837, in 
association with Sir William Cooke, took out a patent 
for an ‘‘improvement in giving signals, and sounding 
alarms in distant places, by means of electric currents 
transmitted through metallic cireuits.’’ From this crude 
instrument grew the system of telegraphy which, modified 
and improved as the art was developed, was extensively 
installed throughout the British Isles. 

To him is due the original conception of the stereoscope, 
which was later improved by Sir David Brewster; also the 
Polar Clock, an ingenious device depending for its action 
on the polarization of light, which does not require (like 
the sun dial), direct sunlight for its operation, but which 


278 Beacon Lights af Science 


is today merely a scientific toy. In 1840 he originated and 
developed, the idea of connecting a number of clocks far 
apart with a central clock, by means of an electric circuit, 
so as to insure their synchronism. He improved the design 
of what is now ealled the Wheatstone bridge (originally the 
invention of Hunter Christy), and employed it successfully 
in the measurement of electrical resistance. 

Wheatstone was really more of an inventor than a dis- 
coverer, but possessed the valuable faculty of adapting dis- 
coveries made by others to useful purposes in the investiga- 
tion of scientfic phenomena, at the same time never failing 
to give due credit to the originator of the idea borrowed. 
This happy temperamental characteristic was recognized 
by the nation, when he was knighted by the King. 


DOPPLER (1803-1853) 
PHYSICS 


CHRISTIAN DOPPLER resided at Salzburg, Austria, re- 
ceived his education at the Polytechnic Institute of Vienna, 
and after graduation, became an instructor in mathematics 
there. Subsequently he held academic appointment at the 
Technical Institute in Prague, the Polytechnicum in Vienna, 
and the Vienna University. 

His contribution to the advance of knowledge consisted 
in the enunciation of what is known as the ‘‘Doppler Prin- 
ciple,’’ which is as follows: 

“‘If a body which is vibrating, and therefore causing 
vibratory waves in the medium surrounding it, such as 
sound, heat, light, electricity, etc., and at the same time 
is moving away from an instrument capable of receiving 
and recording these waves, their number or frequency per 
second is apparently decreased. On the other hand, if the 
vibrating body is approaching the receiving instrument, 
the wave number is increased.”’ 

This, in effect, is simply a statement of an extension to 
heat, light, and electricity, of a principle which for a long 


The Nineteenth and Twentieth Centuries 279 


time had been well known with regard und. For, ifa 
sounding body—a whistling locomotive for instanece—is 
approaching a listener, he perceives that the pitch of the 
note becomes higher as it nears his position, and lower as 
it recedes; which means that, under the first condition, 
more of the air waves per unit of time come to his ear 
and under the second, fewer of them. 

The extension of the principle to those waves in the ether 
which are called light, when coming from a star, or from 
the edge of the rotating sun, makes it possible to determine, 
not only whether the source of light is approaching or 
receding from an observer, but to ascertain with consid- 
erable accuracy, the velocity with which it is moving in 
space. For when the beam of light is split up by the spec- 
troscope into its component colors, there will be a slight 
shift towards the blue end in the ease of approach, and 
towards the red end in the case of recession. And when 
a photographic plate is used to record the radiation, the 
actual change in wave number per second can be measured, 
and thus a close idea obtained of the velocity at which the 
luminous body is moving. 

By the use of this principle, the drift in space of a large 
number of the stars, has been approximately determined. 


LIEBIG (1803-1873) 


CHEMISTRY 


Justus Lirpia was the son of a dealer in dyes, in Darm- 
stadt, Germany. His early education was very limited, 
and at the age of fifteen he was bound to an apothecary 
in the near-by town of Heppenheim. Here, by diligent 
work and economy he accumulated enough to enable him to 
matriculate at the University of Bonn, and later at that of 
Erlingen, where he graduated in 1822 with the degree of 
M.D. His first research and publication in science was on 
the fulminates, those extremely unstable compounds the 
most familiar being the fulminate of mercury, which is 
employed in the manufacture of detonating caps for use 


280 Beacon LInghts of Science 


with high explosives. These monographs attracted the at- 
tention of Alexander von Humboldt, through whom he 
secured favorable letters of introduction to several of the 
noted chemists of the time, and ultimately landed as an 
assistant in the laboratory of Gay-Lussae in Paris. From 
then on his rise was rapid, culminating in-the appointment 
to the chair of chemistry at the University of Giessen in 
1824. There he remained for a quarter of a century, and 
attained a reputation so high as a discoverer and a teacher 
of his science that in 1845 he was created a Baron, and 
in 1852 was tendered the professorship of chemistry at the 
University of Munich, where he remained for the balance of 
his active life. In 1860 he was elected president of the 
Bavarian Academy of Sciences. 

Liebig is regarded as the man whose work in the early 
days of the science of chemistry placed it on its feet syste- 
matically. He was an originator of new methods of analy- 
sis and synthesis, especially in its organic department. 
Though a brilliant lecturer and teacher he was also a not- 
able discoverer. To him, for instance, we owe the discoy- 
ery of chloral, chloroform, aldehyde and a host of previ- 
ously unknown carbon compounds of vast importance in 
the arts. 

He was also a pioneer in the study of the phenomena of 
life, and of what was then called the ‘‘vital force,’’? which 
was assumed to be the active principle or agency in all 
forms of living things. He succeeded in demonstrating 
beyond question that no such a force existed, and that the 
phenomena appearing to require its presence were simply 
exhibitions of energy liberated in the state of animal and 
vegetable heat and motion through the processes of diges- 
tion and assimilation of foods. He was the first to show 
that the transformation of inorganic into organic material 
is the exclusive duty of the world of vegetation, and that 
only by the consumption of the products of that depart- 
ment of life in the shape of fruits, vegetables and grains, 
was it possible for animal life to obtain foods that could 
be changed into tissue and necessary bodily fluids. In fine, 
the now extensive and numerous sciences relating to soil 


The Nineteenth and Twentieth Centuries 281 


fertilization and nutrition have been largely built up on 
the foundation of his work. He is universally accorded the 
honor of having been the founder of the science of agricul- 
tural chemistry. 


MAURY (1806-1873) 


GEOGRAPHY 


MartHew Fontaine MAury was a Virginian by birth, 
but was educated at the Harpeth Academy in Tennessee. 
At the age of nineteen he secured the appointment of mid- 
shipman in the navy, and in 1827 made a voyage around 
the world in the Vincennes. In 1839, having met with an 
accident while on duty in which his leg was broken, so that 
he became a cripple for life, he was given a post in the 
Naval Office in Washington, where he had access to the 
accumulation there of old ships’ logs for many years previ- 
ously. He became deeply interested in these; and from the 
weather records which they gave he constructed a series 
of wind and current charts, which were later embodied in 
his notable work entitled ‘‘The Physical Geography of the 
Sea.’’ This was the first collected body of information in 
regard to marine phenomena. It was published in 1855 
and marked the beginning of a new branch of meteorologi- 
val science which, during the years that have followed has 
been extensively cultivated by a number of investigators. 

To the mariner a knowledge of the location, direction 
and velocity of such major oceanic currents as the Gulf 
Stream in the Atlantic and the Kuroshiwo—better known 
as the Japan—current of the Pacific, is of vital importance, 
while data relating to the minor currents produced by the 
tides, the configuration of coast lines and the revolution of 
the earth on its axis, together with those periodical or 
seasonal atmospheric movements known variously as mon- 
soons, typhoons, hurricanes, ete., are even more necessary 
to aid him in avoiding the perils of the sea. To Maury be- 
longs the eredit of having initiated the investigation of 
these phenomena which, since his day, have been studied 


282 Beacon Lights of Scrence 


and described by Ferrel in his ‘‘ Winds of the Globe’’; by 
Agassiz in his ‘‘Three Cruises of the Blake’’; by Pillsbury 
in the Annual Reports of the U. S. Coast Survey, and by 
Thompson and Blake in their ‘‘Reports of the Scientific 
Results of H. M. 8. Challenger.”’ 

When the Civil War broke out Maury offered his serv- 
ices to the Confederacy, who sent him in 1862 to Europe on 
a political mission. After its termination he went to 
Mexico, and took service under the Emperor Maximilian 
as Commissioner of Emigration. When the government of 
that unfortunate ruler was overthrown he returned to the 
United States, and was appointed to the chair of Physics 
in the Virginia Military Institute, where he remained dur- 
ing the balance of his life. 


AGASSIZ (1807-1873) 


GEOLOGY 


Louis AcAssiz was the son of a clergyman, in Motier, 
Switzerland. After completing his primary studies at Lau- 
sanne in that country, he followed up the higher branches 
at the universities of Zurich and Heidelberg, specializing 
in medicine and zoology. After taking his degree in 1830 
he went to Paris, and studied under Cuvier, becoming his 
ardent disciple. From 1832 to 1846 he was professor of 
natural history at the University of Neuchatel, and during 
that period, in collaboration with James D. Forbes, and at 
times with Arnold Guyot, devoted his summers to studies 
of the Swiss glacial phenomena. The discoveries made by 
these three men have been of the greatest value to science 
in general, and especially to geology, archaeology and an- 
thropology, in explaining the part that has been played by 
the Glacial Era in erosion, and in the history of mankind, 
and the animal world. 

In consequence of his ability and charm as a lecturer, 
Agassiz was invited in 1845 to come to the United States, 
by the Lowell Institute of Boston. In 1846 he was ap- 
pointed professor of natural history in the Lawrence Scien- 


The Nineteenth and Twentieth Centuries 283 


tific School of Harvard University, a position which he 
retained for the remainder of his life. 

Erosion is the process by which the surface of the earth 
is carved into the relief of plain and valley after its first 
distortion and wrinkling into ocean beds, mountain ranges 
and high plateaus by vulcanism, or contraction of the crust 
on cooling. It is the work of the winds, the rivers and 
streams, the falling rain and snow and the ice in glacial 
eras and local glaciers. The first of these agencies does 
mainly finishing work, piling up dunes in arid regions and 
along sea shores, and occasionally in confined areas acting 
like the familiar sand blast in sculpturing rocks into all 
kinds of fantastic shapes. The work done by the rivers and 
streams is necessarily confined to the deepening of their 
channels and the creation of bars along their sides, while 
the rain and snow do little more than fill up depres- 
sions, or find natural lines of travel which later become 
the channels of rivulets and creeks. The ice, however, is 
the great erosive agent, and no more impressive exhibition 
of its capacity in that line is to be found than in the north- 
ern parts of the North American continent, where the great 
sheets of the last glacial era have worn away several thou- 
sand feet in thickness of sedimentary rocks over hundreds 
of thousands of square miles of area, and carried the vast 
cargo of sand, gravel and boulders southward across the 
Canadian border into the United States, finally dropping it 
in the form of a terminal moraine over 2000 miles in 
length which today constitutes the southern divide of the 
St. Lawrence valley and the Great Lakes. 

The erosive work performed by rivers, though insignifi- 
cant as compared with that of ice, may yet be impressive 
and important. The Mississippi carries each year into the 
Gulf of Mexico nearly 270 cubic miles of fine debris. Its 
source in the state of Minnesota being 1462 feet above the 
waters of the gulf, and its length (including its windings) 
about 2500 miles, its average grade is less than 6 inches per 
mile, which makes it a very second rate eroder. Yet prac- 
tically the whole state of Louisiana has been built up by 
it, and it is still steadily extending it into the sea. 


284 Beacon Lights of Science 


The ocean along its shores, where wave action extends to 
the bottom, is also an active erosive agent, though of minor 
importance; while the tides and the shore currents carry 
away the material its waves break down, pulverizes it, and 
distributes it in layers on the near ocean floor. 


GUYOT (1807-1884) 


GEOGRAPHY 


ARNOLD GuyYOT was born in Switzerland, near the town 
of Neuchatel. His early education was obtained at the 
local schools, and completed at the University of Berlin. 
From 1835 to 1839 he was a private tutor in Paris, and 
from the latter date to 1848, the professor of physical 
geography at the College of Neuchatel. He then emigrated 
to America, settling at Boston where, from 1848 to 1854, he 
lectured under the auspices of the Massachusetts State 
Board of Education. From 1855 until his death, he occu- 
pied the chair of physical geography at Princeton Uni- 
versity. 

Guyot’s contributions to the advance of knowledge, were 
largely the outcome of his studies of the phenomena of gla- 
ciers which, among other matters of lesser importance, re- 
sulted in his announcement in 1838, in a paper read before 
the Geological Society of France, of the correct explanation 
of the laminated structure of these rivers of ice. Attention 
having thus been called to this line of investigation, the 
work was carried on by Agassiz and Forbes, and later by 
Tyndall. At the present time, almost entirely as the re- 
sult of the studies of these four men, the work performed 
by ice in erosion, and by the Ice Age in the history of 
animal and vegetable life, has become fairly well under- 
stood. 

To Guyot is very largely due the system of meteorologi- 
eal observation which has made the United States Weather 
Bureau such an efficient organization, and the model upon 
which practically those of all the other nations of the 
world have been built. He also made extensive barometri- 


The Nineteenth and Twentieth Centuries 285 


eal surveys of the Appalachian mountain chain, and pre- 
pared meteorological and physical tables of the eastern 
coastal plain of the country, which have been used ever 
since. 

In the lower portions—the foothills—of a high mountain 
range, the snowfall of a winter ordinarily disappears com- 
pletely during the following summer; but in the higher 
parts, where the precipitation has been greater and the 
summer heat less, there is often a steady accumulation. If 
this process went on indefinitely, it is evident that in due 
time the entire upper parts of ranges and high plateaus 
would be buried under sheets of ice for, as snow accumu- 
lates in depth it packs under the increasing weight, and 
changes gradually into ice. And this is actually what has 
happened in the interior of Greenland and other broad areas 
in the polar regions, where the slope of the surface is gentle. 

But usually a form of relief is provided. As the mass 
and weight increases, the ice begins to move downhill in 
all possible directions—which naturally are those of ravines 
and valleys—carrying with it, and imbedded firmly in its 
under side the gravel, sand and boulders of their slopes and 
floors; and’ on its surface such of the same materials as 
fall down upon it from higher parts. Thus the frozen 
stream becomes a gigantic rasp, or a section of very coarse 
sandpaper, each year cutting deeper and deeper into the 
bottom and sides of the gorge in which it flows. 

When the river of ice reaches lower altitudes where 
summer temperatures prevail over those of winter, the ice 
melts, depositing the surface load of debris it has brought 
down from above, thus forming what are called lateral 
moraines, that is long lines of gravel sand and boulders on 
each side of its path, while at the end another mass of 
the same material is unloaded. So long as a glacier is ad- 
vancing, that is, pushing its way out through the throat of 
a valley or ravine into lower altitudes where the slope of 
the surface is less, the former continue to grow in length 
and height, and no terminal moraine appears. But when, 
as the result of the amelioration of general climatic condi- 
tions, the glacier begins to retreat, the latter commences to 


286 Beacon Lights of Science 


form, steadily invtreasing in mass, height and width, until 
a wall or dam is built up across the valley, and a lake basin, 
or several of them come into existence. 


DARWIN (1809-1882) 


BIOLOGY 


CHARLES ROBERT DARWIN was reared in Shrewsbury, in 
the west of England, where he attended the public school. 
Following this, he worked through two sessions at the Edin- 
burgh University, and then went to Cambridge, graduating 
in 1831 with the degree of B.A. Very shortly thereafter, 
he was offered the post of naturalist to the expedition which 
circumnavigated the globe in H.M.S. Beagle, taking five 
years for the journey. 

Though he attained the age of 73, and in his appearance 
gave the impression of a rugged constitution, yet his frame 
was slight, and the long voyage, with the constant physical 
and mental worry it entailed, left him with an impaired 
digestion, from which he never recovered, and which per- 
mitted him only a limited amount of work per day. Nev- 
ertheless, between 1839 and 1881 he wrote and published 
eighteen books, practically all of which were based on the 
notes collected while on that memorable voyage, though also 
extensively supplemented by information collected after- 
wards, by personal observation, and through correspondence. 
All of these are notable productions. But the ‘‘Origin of 
Species,’’ and the ‘‘Descent of Man,’’ which appeared re- 
spectively in 1859 and 1871, are the two that gave him his 
world-wide reputation, as the discoverer of one of the great 
laws of nature, that of Evolution. 

When the first of these appeared, it aroused the greatest 
interest among educated people everywhere, and largely 
through the extraordinarily able championship of Huxley, 
Spencer, and other leading thinkers of the time, its conclu- 
sions were widely accepted, in spite of the fact that it 
substituted a natural and orderly explanation of phenom- 
ena, that previously had been accounted for by a super- 


The Nineteenth and Twentieth Centuries 287 


natural one. Instead of Creation it offered Development, 
as the actual cause of all forms of life. Naturally such a 
theory could not be harmonized with the teachings of the 
Church, and among its leaders arose its bitterest oppon- 
ents. 

When his second book appeared, advancing the belief that 
not only the human body, but the human mind, was an 
evolutionary product, and that we are akin to the animals 
of the field, the fowls of the air, the fishes of the sea, and 
the trees of the forest, a doctrine so revolutionary in all its 
aspects shook the world like an earthquake. But Darwin’s 
conclusions were based on the firm foundation of observed 
facts, and could not be set aside. They are now uni- 
versally accepted. 

In all his writings, Darwin made no attempt to explain 
evolution. He advanced it as a fact, not as a theory, just 
as Copernicus did, in the case of the motions of the solar 
system, and as Newton in respect of gravitation. In each 
case the How and Why remain unexplained. Since his 
day evolution as a Cause, has been found to be active in 
every branch of science which is capable of being investi- 
gated by the human mind. It is one of the fundamentals 
of the Cosmos. 


FORBES (1809-1868) 


PHYSICS 


JAMES Davin ForRBES was a native of Scotland, and was 
educated at the University of Edinburgh for the law; but 
his inclinations led to the study of physics, and in 1833 he 
became professor of natural philosophy there. His re- 
searches resulted in the important discovery of the polari- 
zation of heat rays, for which he was awarded the Rum- 
ford medal by the Royal Society of London. 

During the years between 1836 and 1848, he devoted his 
summers to the investigation of glacial phenomena, at first 
in Switzerland, in association with Agassiz; and in 1844 
published an account of them, under the title of ‘‘Travels 


288 Beacon Laghts of Science 


through the Alps,’’ which is regarded as a classical produc- 
tion on the subject. In 1851 he made a similar study of the 
glaciers of the Scandinavian peninsula. Two years later 
appeared his final work, ‘‘A Tour of Mont Blane and Monte 
Rosa,’’ on the same subject. 

Those undulations in the ether which affect our sense of 
vision or produce the sensations of heat, are like those which 
travel through a cord when one end of it is fixed, and the 
other vigorously shaken; waves which rise and fall at right 
angles to the direction in which they travel. There is no 
travel in the string, or in the ether, but the impulse in the 
latter does move from its source to the eye, as it does from 
the free end of the string to its fixed end. Each such 
impulse is called a ray and, according to the length from 
erest to crest of its individual undulations, it may be 
either a ray of light, or of heat, or of electrical energy. 
Space is filled with countless billions of them, coming from 
all directions, and moving with undulations whose crests 
and troughs point to all imaginable angles that might be 
conceived on the plane of a circle, perpendicular to their 
course. 

Assume now that across the path of a beam of such rays, 
a thin slice of the apparently transparent mineral tour- 
maline is interposed at right angles to the direction of its 
travel. When it issues from it, it is found that all the 
rays composing the new beam are now undulating in waves 
whose crests and troughs are parallel to each other. Two 
inferences are permissible. Hither the crystal, owing to 
the peculiar manner in which its molecules are arranged, 
has cut off and refuses to pass all except those vibrating in 
a certain plane; or else, in addition to passing them, it has 
compelled all the others to change the angle of their undu- 
lations. It is as if the crystal had a long and extremely 
narrow slit through it, which either cut off all rays except 
those vibrating in planes parallel to its length, or else, if 
passing them, compelled the others to accommodate them- 
selves to the direction of that length. To determine which 
is the case, let there be interposed across the now ‘‘plane 
polarized’’ beam—as it is called—another slice of the same 


The Nineteenth and Twentieth Centuries 289 


mineral, taking care that the face of this second slice is 
parallel to the face of the first. If now the second one is 
revolved in its plane it will be found that in a complete 
revolution of 360° there are two positions exactly 180° 
apart, in which the beam fails to pass through it, while 
halfway between these two it emerges with maximum in- 
tensity. Evidently then, while the tourmaline in thin 
slices 1s apparently transparent, because some rays are 
always striking it in the proper way to make the transit, 
yet it is completely so only in one direction. 

Substances like well-made glass or pure water, being 
strictly homogenous in structure, pass freely—if not too 
thick—all the rays that impinge vertically on their sur- 
faces, and may properly be ealled transparent. Crystal- 
lized substanees are more properly spoken of as translu- 
eent. Each of the seven great crystallographic systems— 
the triclinic, monoclinic, orthorhombic, tetragonal, trigonal, 
hexagonal and isometric—if to any degree translucent, has 
its own way of dealing with the ethereal rays; and these 
having been learned by experience, it becomes possible in 
many cases to determine instantly the class of a mineral 
(and often its membership therein) by subjecting a thin 
slice of it to the action of a ray. Thus the polariscope 
which is the name given to the instrument for polarizing 
rays of all kinds, has become a valuable tool in the hands 
of the mineralogist and geologist. In the applied arts it 
is also extensively employed, as, for instance, in the test- 
ing of raw sugar, to determine the amount of crystallizable 
sugar it contains. 


GRAY (1810-1888) 


BOTANY 


Asa GRAY was a native of the little town of Paris, New 
York. He received a thorough medical education and in- 
tended to follow that profession, but was diverted to the 
study of plants, and became ultimately one of the noted 
botanists of his day. In 1842 he entered the faculty of 
Harvard College as professor of natural history, and re- 


290 Beacon Lights of Scvence 


mained in that position until 1873, when he resigned, and 
devoted the rest of his life to the care of his extensive 
herbarium, which at the time was the most complete on 
the continent. He was a voluminous writer on his spe- 
cialty. 

The work of Gray was mainly along the lines of classi- 
fication and description, for which he had a real genius, 
and which led to several conclusions of great importance. 
One of them was to the effect that species in plants have 
but one place of origin, and spread from there as an effect 
wholly of physical causes, such as prevailing winds, ete. 
He was one of the first American scientists to espouse with 
vigor the doctrines of evolution as enunciated by Darwin. 
Yet having been brought up under strictly orthodox prin- 
ciples, he was unable to cast them aside entirely, and main- 
tained to the last that variation in all departments of 
organic life was guided by a supreme and _ intelligent 
Power, and that evolution as a principle could thus be 
reconciled with the strictest of church creeds. This inabil- 
ity to differentiate between the Creator of the Law, and the 
effects of the law itself, has troubled too many otherwise 
clear-headed indivduals among earnest scientists, as wit- 
ness, for instance, the cases of Cuvier, Lyell and even the 
ereat Newton himself. 

Gray was a veritable apostle of classification in his spe- 
cialty. Previous to his time great confusion had existed in 
the work of naturalists because no international system was 
in existence. About then the British Association for the 
Advancement of Science, in collaboration with like organi- 
zations in the United States, France and Germany, took 
the matter up in earnest, with the result that a system was 
devised which has since been rigidly followed with great 
advantage. Today a name for a new species is not recog- 
nized unless it is in the customary binomial form (which 
originated with Linnaeus), the two words being in the 
Latin language, and agreeing in number and gender. In 
botany the system begins with the four great classes of 
Thallophytes, Bryophites, Pteridophytes and Spermato- 
phytes. Each of these is subdivided into Orders; the orders 


06c 260d Gu1sD 7 saunas fo KwmapprIp puU01q.DN' ©) 


ea Rs 





iis ett eo ine ES ENCRED aa ae ei OR tao 


Pilih Ds 21's 


POE PPLERERRRNAAAELERAEREASERELI (cc LUEBEERANBAL OCs chs SEERRESaasauna 





Diy an 


sail 
HE 
UMUERGIY OF LLNS 





The Nineteenth and Twentieth Centuries 291 


into Families; the families into Genera; the genera into 
Species; the species into Races, and the races into Indi- 
viduals; the last being the popular or familiar name by 
which the plant is known, and which differs in each lan- 
guage. By comparing this with the simple system of 
Dioscorides of Trees, Shrubs and Plants the changes since 
his day become apparent. 

From 1863 until 1873 Gray was president of the Ameri- 
ean Academy of Sciences and Arts, and in 1872 occupied 
that position in the American Association for the Advance- 
ment of Science. He was an honorary or corresponding 
member of many European scientific societies. His botani- 
cal investigations extended into fossil vegetation, and led 
to the direct conclusion that plant fossils from two con- 
secutive geological formations were far more closely related 
than those of two remote formations. This, he naturally 
concluded, was confirmatory of the general principles of 
evolution. 


ANDREWS (1810-1897) 


CHEMISTRY 


THomMAsS ANDREWS was born at Belfast, Ireland, and 
studied medicine and the physical sciences at the universi- 
ties of Glasgow, Edinburgh, Dublin and Paris. After prac- 
ticing as a physician for several years in his native city 
he was appointed in 1845 professor of chemistry at Queen’s 
College, Oxford, where he remained for thirty-four years. 
He then resigned and devoted the rest of his life to re- 
search. 

In 1861, when investigating the properties of certain 
gases, he reached the important conclusion that for each 
one of them there is a definite degree of temperature (or 
absence of it), above which no amount of pressure will 
cause it to change into a liquid. Below that figure a gas 
will sometimes partially liquefy, but precisely at it—called 
the critical point—it passes at once into the liquid state. 
This point differs for each gas. Similarly it has since been 


292 Beacon Lights of Science 


found that for each of them there is also a definite pres- 
sure and temperature figure at which alone the liquid will 
become a solid. In consequence of this discovery, all the 
known gases have since been reduced to the liquid econdi- 
tion, and all but helium to that of a solid. 

Andrews also made a special study of ozone, and to him 
is due the most of what is known at the present time of the 
properties of that substance. Technically considered, it is 
an allotropiec form of the elementary gas oxygen; that is, 
one of the states which the element can assume without loss 
of its elementary character, but which is accompanied by 
marked differences in some of its physical properties. A 
number of the elements possess this capacity, notably sul- 
phur, phosphorus and carbon, and many chemists hold 
that allotropism can occur with any of them, given the 
proper conditions, inasmuch as it seems to be wholly a 
molecular phenomenon. The molecule of normal oxygen 
consists of two atoms (O,). When in that state it is color- 
less, tasteless and odorless. If reduced to a liquid it is 
transparent, displays a faint blue tint, and begins to boil 
and return to the gaseous form at — 181.4° C. In the solid 
state it presents a dead white appearance. The molecule 
of ozone consists of three atoms of oxygen (O,), possesses 
a faint bluish color, but also a strong but not unpleasant 
odor. At — 100° C. it becomes, under the proper pressure, 
a very deep blue—almost a black—liquid, which begins to 
boil at the temperature of — 106° C. 

Ozone was first observed in 1785 by the Dutch student 
Van Marum, who produced it undesignedly when passing 
an electrical current through some oxygen, and detected 
its peculiar odor. He also noticed that the same effect 
was always produced in the immediate vicinity of a fric- 
tional electric machine. In both cases he concluded that 
it was ‘‘the smell of electricity.’’ In 1801 the same odor 
was observed by an English chemist named Cruikshank, 
who was engaged in decomposing some water by electricity. 
This time the phenomenon was ascribed to the accidental 
presence of a little chlorine which, if in very small quanti- 
ties, has a somewhat similar effect on the olfactory neryes. 


The Nineteenth and Twentieth Centuries 293 


Finally, in 1840, the attention of the German chemist, 
Schonbein, was drawn to the matter, and after a prolonged 
research he announced in 1845 the discovery of a new gas, 
giving it the name it now bears. A few years later the 
French chemist, Soret, demonstrated its true character as 
merely an allotropic form of oxygen. 

Ozone is always present in minute quantites in the at- 
mosphere, and in much larger quantities after a violent 
thunder storm, during which it is produced, giving the 
characteristic fresh and clean effect so noticeable after such 
a storm has passed away. It is a more powerful oxidizing 
agent than normal oxygen. Under confinement it will re- 
duce iron, copper, mercury and even silver from the metal- 
lic state to that of the oxide, and will rapidly destroy rub- 
ber and vuleanite. It is a powerful bleaching agent and 
germ destroyer. The latter property is sometimes employed 
in purifying the air in hospitals and clinical amphitheatres. 
Whenever and wherever the atmosphere produces an ex- 
hilarating effect, and impresses one as unusually fresh and 
clean, it will be found to contain temporarily more than 
its average content in ozone. The phenomenon is nature’s 
way of purifying the sea of air we live in when, for any 
reason, it has become abnormally impure and unhealthful. 


DRAPER (1811-1882) 


CHEMISTRY 


JOHN WILLIAM DRAPER was brought up near Liverpool, 
England; and received his education at a Wesleyan school, 
and at the London University. At the age of twenty he emi- 
grated to America, entered the University of Pennsylvania, 
eraduated there with the degree of M.D., and was at once 
appointed to the chair of natural philosophy at Hampton 
College, Virginia. In 1839 he became a member of the 
faculty of the University of New York. A little later, he 
joined with others in organizing the medical school of that 
institution, becoming its first professor of chemistry and 
physiology. 


294 Beacon Lights of Science 


Dr. Draper’s principal contributions to the increase of 
knowledge were in the field of physical and photo-chem- 
istry. By means of his actinometer—produced in 1842— 
he effected the quantitative combination of hydrogen and 
chlorine for the first time, solely under the action of light ; 
and while his apparatus and methods were much improved 
later by Bunsen, Roscoe, Elder and Rigolet, yet to him 
belongs the credit of having led the way. He was also the 
first to demonstrate that the different colored rays into 
which a beam of sunlight ean be split, exercise an unequal 
influence on the decomposition of carbon dioxide by the 
green pigment (chlorophyl) of plants. He further showed 
that all parts of the solar spectrum (the invisible as well 
as the visible) are capable of initiating chemical action of 
some kind. Finally, though Daguerre was the real discov- 
erer of the art of photography it was not until improve- 
ments were made in its technic by Draper, Archer, Maddox 
and others, that it became a practical one. 

He was a voluminous writer on many different subjects, 
and perhaps is best known by his ‘‘ History of the Intellec- 
tual Development of Europe,’’ published in 1863, which, 
though somewhat discredited at the present time, was a 
most scholarly production, and is still read, because its 
main conclusions have been verified by the lapse of time. 


LEVERRIER (1811-1877) 


ASTRONOMY 


URBAIN JEAN JOSEPH LEVERRIER spent his youth at Saint 
Lo in northern France, and after passing through the 
Eeole Polytechnique at Paris, where he exhibited high 
mathematical ability, became a government employee. At 
the age of thirty-five, in consequence of the publica- 
tion of a monograph entitled ‘‘Tables de Mercure,’’ and 
several others of note on the secular inequalities of plane- 
tary motions, he was elected a member of the French 
Academy, and at the suggestion of Arago the astronomer, 
undertook an exhaustive investigation of the perturbations 


The Nineteenth and Twentieth Centuries 295 


that had been detected in the motions of the planet Uranus, 
and to a lesser degree in those of Saturn and Jupiter, the 
cause of which was conjectured to be due to the existence 
of another yet undiscovered member of the solar system, 
beyond the orbit of the three mentioned. After prolonged 
and laborious calculations, Leverrier indicated the boun- 
daries of a region in space where the supposed planet 
should be found, and when this area was examined by the 
astronomer Galle of Berlin, the planet Neptune was dis- 
covered on September 26, 1846, in very close proximity to 
the exact location assigned by Leverrier. 

It is proper here to note that while the latter was at 
work on this problem, the English astronomer, Adams, an 
equally cifted mathematician, was also engaged on the same 
calculation, and really finished it first. He gave his results 
to the English observer, Challis, who actually found the 
planet at the place indicated, and between the dates of 
August 4th and 12th of the same year. But Challis neg- 
lected working up the notes of his observations for more 
than a month, and so failed to recognize the object as a 
planet, until after its detection by Galle had been published. 

As Neptune travels in an orbit whose mean distance from 
the sun is 2,800,000,000 of miles, and requires 164 years to 
complete one revolution around that luminary, its discov- 
ery by these two astronomers almost simultaneously, is 
rightly regarded as one of the most remarkable of human 
accomplishments in the domain of mathematics. 

In recognition, Leverrier was given the grand cross of 
the Legion of Honor, a professorship in astronomy in the 
faculty of Sciences in Paris, and the directorship of the 
Paris Observatory, which honorable positions he held dur- 
ing the remainder of his life. 


BUNSEN (1811-1899) 


CHEMISTRY 


Rospert WILHELM BUNSEN was born at Gottingen, Ger- 
many, and educated at the University of Heidelberg. After 


296 Beacon Lights of Science 


having held professional positions at Cassel, Marburg, and 
Breslau, he was appointed to the chair of chemistry at 
Heidelberg, a position which he held until his retirement 
in 1880 from the field of instruction. 

He was a noted investigator and experimenter in chem- 
istry and physics, and contributed extensively to the ad- 
vancement of science. One of the most useful of his devices 
is known as the Bunsen burner, by which, employing ordi- 
nary illuminating gas, an almost invisible flame of very 
high temperature is produced. Its principle is now uni- 
versally employed wherever cooking with gas is done. 

Bunsen’s great achievement, however, was the develop- 
ment of the methods of spectrum analysis, the foundation 
of which had been laid by Fraunhofer’s identification and 
explanation of the dark absorption lines in the solar spec- 
trum. In collaboration with Kirechhoff—to whom almost 
equal credit is due—the investigations of the two, led first, 
to the discovery of the metals caesium and rubidium, and 
later of a number of others. In effect Bunsen and Kirch- 
hoff were the developers of the science of chemical spec- 
troscopy. Following their lead this department of science 
has since been extended into the field of astronomy with 
very marvelous results, so that today we know much as to 
the kind of matter of which the stars, the nebulae and the 
comets are composed. 

Bunsen devised an economical method for the produc- 
tion of the metal magnesium from its ores, and was the first 
to employ the brilliant white light produced in its combus- 
tion (which is rich in actinic rays), in photography, thus 
making possible the taking of pictures indoors and under- 
sround. He also invented the filter pump, a form of gal- 
vanic cell which is much in use, and several other appli- 
ances that are indispensable in laboratory work. 

The colorless flame of the Bunsen burner, and the blue 
and smokeless flame of the ordinary cooking range and 
open fireplace, are produced by allowing air to become well 
mixed with the gas before it issues from the aperture where 
combustion takes place. Being thus supplied freely with 
all the oxygen it requires, all the carbon it contains is com- 


The Nineteenth and Twentieth Centuries 297 


pletely converted into carbon dioxide, and all the hydro- 
gen into water vapor, giving no opportunity for unburned 
carbon in the form of smoke or soot to form. 


PACINI (1812-1883) 


PHYSIOLOGY 


Finippo Pacinti was born at Portola, Italy, studied medi- 
cine at Florence and Pisa, and became professor of anatomy 
at the University of Florence, where he remained until he 
retired from active life. 

He is noted as the discoverer of the peripheral nerve ter- 
minations, which are known as the ‘‘corpuscles of Pacini.’’ 
These are minute bodies, attached to and enclosing nerve 
terminations in various parts of the body; in man chiefly 
in the subcutaneous tissues, and form little bulbs, with the 
axis cylinder of the nerve running into them. It is because 
of them that we possess the sense of touch. 

This sense, which exists everywhere—but in different de- 
erees—on the surface of the body, should not be con- 
founded with the sensation of pain produced by a cut or 
bruise, or with temperature perception, though all three 
are carried to the brain by the same set of nerves. Certain 
of them terminating just under the outer skin and mainly 
in the extremities of the hands and feet, are also fitted with 
end bulbs. These are the true touch organs. On the other 
hand, the Pacini corpuscles are much more widely dis- 
tributed over the body, but also lie deeper in the skin, and 
generally in the tissue under it. They are.especially abun- 
dant on the palms and on the inner side of the fingers and 
under side of the toes. It has been suggested that these in 
man are degenerating organs which formerly came much 
closer to the surface, and were of great use in his life 
among the trees. 

As to the true touch bulbs, it is the view of some physi- 
ologists that those at the end of the fingers have the special 
power of conveying to the mind what may be ealled ‘‘the 
impression of nearness’’ to an object being approached. 


298 Beacon Lights of Science 


Whether or not there be any foundation for this, the fact 
remains that they can acquire the ability to achieve very 
remarkable feats. One has only to watch the performances 
of an expert piano player or typist, to become convinced 
that the fingers can learn to move from position to position 
on the keyboard of a piano or typewriter, without the aid of 
the eye, which, wholly preoceupied in reading notes or 
words, conveys their significance to the brain, and seems to 
leave with confidence to the latter the guidance of the won- 
derful muscles of the arms and hands. 

An instrument called the aesthesiometer has been de- 
vised to ascertain the relative acuteness of the sense of 
touch on various points of the body. Excluding the eye as 
untouchable, the tip of the tongue is the most sensitive, 
and closely following in degree is the under side of the 
terminal parts of the fingers. Very much less sensitive is 
the end of the nose, and the white part of the lips. Least 
sensitive of all is the back, except directly along the spine. 


DANA (1813-1895) 


NATURAL HISTORY 


JAMES DwicHt Dana was born at Utica, New York, his 
parents having been of New England nativity and ancestry. 
His early education was acquired in his home town, after 
which he entered Yale college. Upon graduation he was 
offered a position as instructor in the United States navy, 
which afforded him an opportunity for travel in several 
parts of Europe. In 1836 he was appointed assistant to 
Professor Silliman at Yale, and while serving in that 
capacity published his first important work ‘‘A System of 
Mineralogy,’’ which at once became a standard reference 
bock in its specialty throughout the world, and has re- 
mained so ever since. From 1838 to 1842 he was a member 
of the United States Exploring Expedition under Com- 
mander Wilkes—whose field was in the southern Pacific 
ocean—in which he specialized on the subjects of mineral- 
ogy, meteorology, hydrography, corals and crustacea. He 
brought back with him 230 entirely new species of corals, 


The Nineteenth and Twentieth Centuries 299 


and 638 of crustacea. He also wrote the narrative of the 
journey. In recognition of his great services to science 
on this expedition, he was appointed in 1850 to the chair 
of natural history at Yale, where he remained for the suc- 
ceeding forty years, an honored and highly appreciated 
member of its faculty. 

Corals were originally classed as among the zoophytes 
by Cuvier, by which term he meant those low forms of 
animal life that are fixed to a definite position and place, 
and have the appearance in most cases of growing plants. 
The word is no longer used in the current system of classi- 
fication. In its place the species it covered are known as 
hydroids, corals and sea anemones. The last two belong 
to the class anthozoa, and constitute one of the most won- 
derful divisions of the animal world. 

Coral is a calcareous, galatinous or horny product, which 
is secreted from the water of the sea by that strange form 
of animal called the polyp (many footed). After passing 
through its organism, the refuse material is excreted, and 
deposited around it, after much the same process by which 
the oyster constructs its shell, except that in the case of 
the coral the structure keeps on growing indefinitely, and 
like a plant, while each polyp, during its brief existence, 
occupies a minute cell inthe material so built up, reproduces 
itself by a process of budding, and then dies. The individ- 
ual is little more than a minute and formless speck of 
protoplasm which, when taken out of the water when alive, 
drains away in the state of a watery slime from the little 
cell in the body of the coral which was its home. When 
alive, and in its normal condition and situation, it protrudes 
portions of itself like little fingers or hairs, from the en- 
trance of its cell, and by means of these finds and absorbs 
its nourishment. These fingers or tentacles are supplied 
with nerves, and are extremely sensitive. If touched by 
a foreign and objectionable body they are immediately 
withdrawn, and only reappear slowly and cautiously. Un- 
der normal conditions they are continually protruded, and 
by waving about collect the nourishment necessary for 
their growth. 


300 Beacon Lights of Science 


In most eases these polyps exist in colonies, each indi- 
vidual leading apparently a completely solitary life, and 
having no association with or relation to its immediate 
neighbors even though the cells which constitute their 
homes are very eclese together. The coraline forms pro- 
duced are of almost infinite variety, and though the prod- 
uct of each individual in building is extremely small, the 
combined products are enormous, consisting of the forma- 
tion of islands and groups of islands, and of barrier reefs 
hundreds of miles in length. They ean live only in clean 
water, and in depths less than 125 feet, and also require a 
temperature of 68° F. or over, which is obtainable only in or 
near the tropics. The color of coral is generally some shade 
of white or gray. But in the Mediterranean and Red seas, 
and in the Persian gulf a red variety is found which is 
much prized for jewelry and ornamental purposes. At 
certain places in the Pacific a coal black kind oecurs, which 
bring even a higher price than the red. Both of these will 
take a beautiful polish. 

Dana’s great services to science were recognized abun- 
dantly during his lifetime. In 1854 he was elected presi- 
dent of the American Association for the Advancement of 
Seience, and later became a member of the Royal Society of 
London, the Institute at Paris and the Academies of Ber- 
lin, Vienna and St. Petersburg. In 1872 he was awarded 
the Wollaston medal of the British Geological Society, and 
in 1877 the Copley medal. He was the originator of the 
modern theory—now universally accepted—of mountain 
folding and formation as the result of lateral pressure; and 
taught that valleys are, with rare exceptions, entirely prod- 
ucts of erosion; and that in fossils, the individuals that 
compose a species, are almost endlessly diverse in form 
detail. 


BERNARD (1813-1878) 


PHYSIOLOGY 


CLAUDE BERNARD was brought up in the town of St. 
Julien in eastern F'rance. He studied in Paris for the medi- 


The Nineteenth and Twentieth Centuries 301 


cal profession, received his degree in 1853, and in the 
following year was elected to the chair of physiology in the 
faculty of sciences in that city. Shortly afterwards he 
became a member of the French Academy, and in 1855 ac- 
cepted the professorship of experimental physiology at the 
Collége de France, a position which he held for the balance 
of his active life, and where his researches on the functions 
of the liver and the alimentary canal, the action of the 
saliva and the gastric juice in the digestion of food, were 
epochal in their results, making clear for the first time in 
history the part taken by the organs of the trunk in the 
nourishment of the body by food, the replacement of worn- 
out tissue, and the elimination of material no longer needed 
or unsuitable for use. Of especial importance was his 
demonstration of the fact that the blood which enters the 
liver does not contain sugar, while that which leaves the 
organ and goes from there to the heart is well charged with 
that substance. He also made important discoveries in 
relation to the action of certain nerves on the digestive 
organs, showing, for instance, that the formation of sugar 
in the liver could be interrupted by the division of the 
pheumogastric nerve at a certain place; and that the dis- 
ease known as diabetes could be produced by a puncture of 
the fourth ventricle of the brain, from which this nerve 
proceeds. In recognition of the great value and important 
character of these discoveries, Bernard was three times 
awarded the grand prize of the French Academy of Sci- 
ences. At his death, so high was his standing in the esti- 
mation of his countrymen that his funeral obsequies were 
conducted at the public expense, an honor which had 
never before been conferred on a scientific man in that 
country. 


VON MAYER (1814-1878) 


PHYSICS 


JuLIuS Ropert von MAYER was a native of Heilbronn 
in Germany, and studied medicine at Tiibingen and at the 


302 Beacon Lights of Science 


universities in Munich and Paris. He then went to Java 
(1840) and became interested in the subject of animal heat 
as shown in the temperature of the blood. This led to the 
study of the phenomena of heat in general, which in its 
turn drew his attention to other forms of force. In 1842 
he published in Annalen der Chemie his preliminary 
conclusions of the fundamental identity of the forces be- 
hind the phenomena of heat and motion, which constituted 
the first public announcement of the character of these 
two exhibitions of energy. In 1845, and again in 1848 he 
published monographs in which his further theories on 
the subject were stated, and finally in 1851 his ‘‘ Bemerk- 
ungen tiber das Mecanische Aequivalent der Warme,’’ in 
which he gave a figure for the mechanical equivalent of 
heat, that is, a calculation of the amount of motion that 
could be produced by a given quantity of heat properly 
applied. And while this result differed considerably from 
the figure accepted today, to him belongs very properly 
the credit of having first conceived the principle now known 
as the Conservation and Correlation of Energy, which was 
later expanded by Joule and brought to fruition by Helm- 
holtz. 

At the present time all the forms of force with which 
we are acquainted—motion, heat, light, magnetism, elec- 
tricity and chemical affinity—are known to be different 
exhibitions of one universal entity called Energy. Less 
than a score of years ago the latter was defined as ‘‘a con- 
dition or attribute by which matter can effect changes in 
other matter.’’? Since then, matter itself—the atoms of the 
various elements—has been shown to be nothing more than 
one or more protons (units of positive electricity), sur- 
rounded by one or more electrons (units of negative elec- 
tricity), the nature and properties of each atom—as those 
of hydrogen, sulphur, gold, uranium, ete.—being deter- 
mined solely by the number of protons and electrons of 
which it is composed. A marvelous advance for a period of 
eighty-odd years. 

In Mayer’s day it was believed that all the phenomena 
of life in the vegetable and animal world were exhibitions 


The Nineteenth and Twentieth Centuries 303 


of a form of energy called the ‘‘vital force.’’ Today we 
know that vitality, whether mental or physical, is the result 
of chemical action and reaction produced by the changes 
which food undergoes in its passage through the living 
organism. Yet back of all these wonderful revelations 
there remains in the mind of man the consciousness that 
the whole story has not yet been told; that there is still 
a revelation to come, sometime and somewhere, which will 
explain the sense of Personality that is inherent in all of 
us, and that seems to be separate from and above all pres- 
ent conceptions of that invisible entity we call energy, and 
its visible and tangible representative that is denominated 
matter. 


ANGSTROM (1814-1874) 


PHYSICS 


ANDERS JONS ANGSTROM was born at Lodg, Sweden, 
and received his education at the University of Upsala. 
After graduation he became in succession, a tutor, the 
keeper of the astronomical observatory, and full professor 
in physics. From 1867 until his death he was secretary of 
the Swedish Royal Society of Science. He was a writer of 
note on the subjects of heat and magnetism, but his out- 
standing achievements were in the field of optics. In his 
book entitled ‘‘Studies on the Solar Speectrum’’ published 
in 1869, he gave his determinations of the wave lengths of 
those dark lines in the spectrum which, from the name of 
their discoverer, are known as the Fraunhofer lines. His 
researches and discoveries in this department of science 
were so novel, and so fruitful in extending our knowledge 
of the properties of light, that his name has been adopted 
among scientists to express the unit wave whose length 
from crest to crest is one ten-millionth part of a millimeter, 
the millimeter being the one-thousandth part of the meter, 
which, itself measures about 3914 inches, or say 314 inches 
more than a yard. 

Those ethereal undulations to which the human eye is 


304 Beacon Lights of Science 


sensitive, and which, when combined in sunlight, produce 
in the brain the sensation of white light, and when sep- 
arated from each other in the spectrum (or in the rain- 
bow), yield the impressions of the seven primary colors— 
violet, indigo, blue, green, yellow, orange and red—are 
so short that, in the case of yellow light, 1700 crests and 
troughs occur in the length of a millimeter. Now the hu- 
man eye, and the brain behind it which interprets the im- 
pression of the outside world conveyed to it by the organs 
of vision, is so constituted that it can respond to (or see) 
only those undulations which number from 1350 to 2500 
per millimeter, the lower figure corresponding to the deep- 
est shade of red, and the higher to the deepest tint of 
violet that can be detected. But beyond these compara- 
tively narrow limits at both ends of the color spectrum, lie 
regions of invisible light that have been unknown to man 
until within the last fifty years. Those beyond the violet 
are spoken of as the ultra-violet, or high frequency undula- 
tions, and among the first of them are the so-called actinic 
rays, which are responsible for what happens on the photo- 
oraphic plate when exposed. Beyond them are waves that 
can be detected by quartz prisms, glass prisms becoming 
opaque at frequencies of about 3300 per mm., with the 
fluorescent screen. But when the frequencies approached 
5400 per mm. the quartz becomes also opaque to them. At 
this stage of the investigation a highly skillful German 
technician or instrument maker, named Schumann, devised 
in 1896 what is known as the diffraction grating, which 
proved to be a new door into the chamber of mysteries. 
This consisted of a plate of highly polished speculum metal 
—a special alloy of high reflective power composed gener- 
ally of ten parts of copper to one of tin, but also of equal 
parts of steel and platinum—on which were engraved by 
a diamond point a series of parallel lines so close together 
that 15,000 of them were ruled side by side on each inch 
of its width. This plate was then placed in an air-tight 
metallic box fitted with a window made of the transparent 
mineral fluorite (fluorspar), and the air extracted until 
a high vacuum existed. When light was then admitted 


The Nineteenth and Twentieth Centuries 305 


through the window and fell upon the plate, Schumann was 
able, by means of the reflections from it, to detect undula- 
tions so minute that 8500 of them were compressed within 
the length of a millimeter. Subsequently, Lyman, of Har- 
vard University, by an improvement on this device, pushed 
his way still further into the ultra-violet region, until he 
was able to detect rays of nearly 10,000 frequency. Finally 
during the last ten years, Mosely, the American physicist, 
assisted by the German, Laue, and using a still more re- 
fined tool called the ‘‘crystal grating spectometer’’ reached 
wave lengths so minute that those ranging from 1,;000,000 
to 100,000,000 per millimeter could be detected. These 
proved to be the vibrations set up by the electrons 
and protons themselves which are now known to be the 
sole constituents of the atoms of the chemical elements, of 
which matter of all kinds known to our senses are composed. 

In the other direction, that of the infra-red, Langley, 
the American physicist, began explorations in 1881, en- 
countering first the so-called heat rays, which we cannot 
see until a dull red temperature is reached, but which we 
can feel with ease, thus indicating that in one direction 
our sense of touch is more delicate than that of vision. In 
his journey down these invisible parts of the solar spec- 
trum he passed through ranges of undulations from those 
of 1350 per millimeter at the lowest border of vision, down 
to 190 for the same length, all being temperature rays, the 
presence and dimensions of which became appreciable by 
means of his device, the thermopyle. Following his lead, 
Rubens of Berlin, using the quartz-mercury lamp as a 
source of radiation, pursued the investigation down to 
waves as long as three per millimeter. 

When the Hertzian ethereal undulations were detected in 
1896, it was found that the shortest of them—as produced 
by the oscillation back and forth of electrical discharges 
between the condenser plates of a radio installation—was 
six-tenths of a millimeter in length, while beyond them were 
first the waves used in amateur telegraphy, with lengths 
ranging from 50 to 350 meters from erest to crest, and 
still further on those employed in long distance telegraphy 


306 Beacon Lights of Science 


and telephony, with lengths up to 3000 meters and more. 

From this brief outline of the capacity of the ether of 
space to transmit under varying conditions undulations so 
small and so long, the conclusion has been drawn, first, 
that waves still longer will ultimately be detected; and sec- 
ond, that what is at present called by electricians a ‘‘static 
electric field,’’ is nothing more than a region filled with 
ethereal undulations of unlimited, or perhaps more cor- 
rectly, infinite length. 


HOOKER (1817-1911) 


BOTANY 


JOSEPH DALTON Hooker, the son of Sir William J. 
Hooker, the director of the famous Kew Gardens in London 
from 1841 to 1865, was born at Glasgow, Scotland, and 
was educated for the medical profession at the university 
in that city. But immediately upon his graduation in 1839 
he announced his determination to devote his life to botan- 
ical research, and with that end in view joined the expedi- 
tion then being fitted out by Sir John Ross in the two ships 
Erebus and Terror, for the exploration of the coasts of 
the Antarctic continent. On its return in 18438 he brought 
back 5340 plant specimens from that supposed region of 
desolation. These he described in six quarto volumes, 
which were published in the years between 1844 and 1860. 
In 1847 he undertook a three years’ journey through the 
Himalaya mountains, where he made a large collection 
which was presented to the Calcutta Botanical Gardens. 
He then engaged in a study of the flora of peninsula India; 
and when that was completed went to Morocco, and ex- 
plored the chain of the Atlas mountains for new plants, 
making, for the first time for a European, the ascent of its 
highest summit, known locally as the Jebel Ayashi, which 
towers to the height of 14,600 feet. 

In 1855 he was made assistant director of the Kew Gar- 
dens under his father, and when the latter died in 1865, 
succeeded to his position, which he also retained during 
the remainder of his active career. 


The Nineteenth and Twentieth Centuries 307 


To the average reader the devotion of an entire lifetime 
to the collection and description of plants, may seem an 
excessive price to pay for the accumulation of details of 
knowledge that are, for the most part, embalmed in mono- 
eraphs and volumes written in a language so technical as 
to be quite beyond the grasp of all but a few who have 
also made a specialty of the subject, and many, even among 
the educated, will question the value of such efforts. Yet 
experience has demonstrated beyond controversy that only 
patient labor of that kind in any field of research will 
yield information of permanent value. No matter how 
trivial and unimportant at the time these may seem, every 
item of knowledge so gained takes its proper place, sooner 
or later, in the mosaic that science is steadily and humbly 
constructing as the representation or negative of the sub- 
lime work of the Creator of this marvelous world. 

The Hookers, father and son, during the seventy years 
in which the Kew Gardens were continuously under their 
control, not only made it the greatest of botanical institu- 
tions and exhibitions, and one that is annually visited by 
thousands of students from all parts of the civilized world, 
but, as has been amply proved, a source from which the 
new knowledge of the properties and usefulness of plants, 
has resulted in an enormous extension of the commerce of 
Great Britain in products of the soil at home, and in her 
numerous colonies. 


JOULE (1818-1889) 


PHYSICS 


JAMES PRESCOTT JOULE was a native of Salford, in Eng- 
land, and though inheriting a handsome property and busi- 
ness, became deeply interested in physics and electricity. 
He was educated mainly at home, under private tutors. At 
the early age of nineteen he had invented an electromag- 
netic motor, and was able to demonstrate mathematically, 
that in the process of electrolysis, the amount of heat ab- 
sorbed, was equivalent to that produced during the original 


308 Beacon Lights of Science 


combustion of the elements employed. He therefore was 
the first to announce a mechanical equivalent for heat, and 
though the figure he gave was considerably in error, yet 
the principle on which he based his calculations was right. 

It was in the year 1847 that, in a public address, he 
stated the doctrine of the Conservation of Energy, to the 
effect that energy, like matter, can neither be created nor 
destroyed, and that the total energy of the universe was a 
fixed and constant quantity. From this premise results 
the following conclusions: 

1. That energy, in any form, may be changed into energy 
of any other form; which is the doctrine of the Correlation 
and Transformation of Energy. 

2. That when energy in any form apparently disappears, 
an exact equivalent of some other form or forms takes its 
place ; which is the doctrine of the Conservation of Energy. 

3. That when energy undergoes transformation, or trans- 
ference from one body to another, the process is not com- 
pletely reversible; but that if some of the energy is recoy- 
ered in its original form, a residual portion reappears in 
what is called a lower form. This is the doctrine of the 
Degradation and Dissipation of Energy. 

Joule’s announcements on this important subject made 
practically no impression at the time, but was later taken 
up by other men more widely known (as Lord Kelvin), 
thoroughly approved, and due eredit given him for the 
years of patient investigation and experimentation he had 
devoted to that, and other kindred subjects. In recognition 
of those in the field of the electrical sciences, his name has 
been adopted by the International Science Convention, like 
that of Watt, Ampére, Volta, Ohm, Faraday and Henry, 
to express the electrical unit of work, which is: ‘‘The work 
done in one second, when the rate of working is one watt,’’ 
or, expressed in another way, ‘‘the work done in one sec- 
ond in maintaining a current of one ampere, against a 
resistance of one ohm.”’ 

Joule was awarded the Copley, and several other medals, 
and numerous honors from universities and scientific so- 
cieties throughout the world. 


The Nineteenth and Twentieth Centuries 309 


FOUCAULT (1819-1868) 


PHYSICS 


JEAN BERNARD LEON FOUCAULT was a native of Paris, 
and was educated for the medical profession; but becoming 
interested in physics, he devoted the most of his life to 
investigations in that department of science, and to the 
invention and perfection of devices and tools for physical 
experimentation. In 1845 he was appointed scientific edi- 
tor of the Journal des Debats, and in 1850 received the 
decoration of the Legion of Honor. In recognition of his 
eminent services he was elected physicist at the Paris Obser- 
vatory in 1854, a position which he held up to the time 
of his death. 

Although Roemer had determined by ealeulation based 
on astronomical observation (the eclipses of the satellites 
of the planet Jupiter), that light travels in space at the 
approximate velocity of 186,000 miles per second of time, 
Foucault, working in friendly competition with Fizeau, 
demonstrated the fact by mechanical means. The appa- 
ratus devised by the former was so compact, and yet so 
delicate and exact, that it could be operated indoors. That 
of Fizeau, on the other hand, required much space, and 
was not quite as precise. In both, a narrow beam of light 
was thrown on a mirror revolving at high speed, from which 
it was reflected to a train of mirrors, which brought it back 
exactly to its source, or would do so if its velocity had been 
instantaneous. In both arrangements, devices were intro- 
duced. between the start and the finish of the journey of the 
beam, which were capable of measuring the slight deflec- 
tion resulting from the time consumed in the transit, from 
which its rate of speed could be calculated. The two re- 
sults were in substantial agreement, and confirmed the fig- 
ure deduced by Roemer in 1675. It is interesting to note 
that, when these conclusions were examined by the com- 
mittee of the Academy of Sciences—who had offered a prize 
of 10,000 franes for a demonstration—the award was made 
to Fizeau, because his method was more easily compre- 


310 Beacon Lights of Science 


hended by a layman, and was also more spectacular, while 
that of Foucault was adjudged more delicate and precise. 

Foucault demonstrated the fact of the revolution of the 
earth on its axis, by means of the diurnal rotation of the 
plane of oscillation of a long pendulum. He was the in- 
ventor of the gyroscope, of the polarizing prism, and of the 
parabolic reflecting telescopic mirror. He also devised a 
modification of the Watt governor for steam engines, and 
a method of observing direct sunlight without injury to the 
eye. 


‘ADAMS (1819-1892) 


ASTRONOMY 


JOHN CoucH ADAMS was a native of the county of Corn- 
wall, England. He developed at an early age a fine talent 
in mathematics, and after completing his primary educa- 
tion in Cornwall entered Cambridge. Here he distinguished 
himself so greatly in his specialty that after graduation he 
was appointed a mathematical tutor. 

The planet Uranus, which was discovered in 1781 by Sir 
William Herschel, which travels around the sun in 84 years 
at a mean distance of 1,782,000,000 miles, had exhibited 
from the first certain irregularities in its movements, that 
could not be accounted for satisfactorily by the gravitative 
action of the two large planets Saturn and Jupiter, whose 
orbits are within that of Uranus; and early in the nine- 
teenth century astronomers reached the conclusion that the 
solar system must contain still another planet, with an 
orbit greater than that of Uranus. In 1848 Adams set 
himself the task of finding it by purely mathematical rea- 
soning, based upon the laws of gravitation as deduced by 
Newton. The sole foundations for his calculations were the 
known perturbations exhibited by Uranus in a certain part 
of its orbit where, supposedly, the unknown body was at 
its nearest position. 

Adams spent nearly two years in this study, and finally 
assigned a definite position in the heavens to a body of 


The Nineteenth and Twentieth Centuries 311 


definite mass, and communicated this conclusion to the 
Royal astronomer, with the request that the sky be ex- 
amined in the vicinity for a new planet. The search was 
made, and a moving body found within two degrees of 
the place assigned for it; but, unfortunately for Adams, 
the searcher deferred reporting his discovery until he could 
complete enough additional observations to enable him to 
assure the mathematician that the heretofore supposed star 
was really a planet, and to compute its orbit. 

Meantime the French mathematician, Leverrier, had been 
studying the same problem, and had also figured out a 
position. His conclusion were communicated to the Ger- 
man astronomer, Galle, who not only found the planet 
within one degree of the place indicated, but immediately 
advised Leverrier, who at once made public his discovery 
before Adams was able to announce his. 

The new planet, which was given the name of Neptune, 
was found to have a diameter of 34,800 miles. Its mean 
distance from the sun is 2,792,000,000 miles, and its period 
of revolution 165 years. It has one satellite, which travels 
around it in five days and twenty-one hours. It has been 
thought by a few astronomers that our system contains still 
another one with an orbit beyond that of Neptune. But 
it has not been found. And the heavens have, during recent 
years, been so accurately mapped photographically, that 
its existence is very doubtful. It is a curious and still un- 
explained fact, that while the satellites of Mars, the earth, 
Jupiter and Saturn travel from west to east around their 
primaries, those of Uranus and Neptune move in the oppo- 
site direction, from east to west. 


STOKES (1819-1903) 


PHYSICS 


GEORGE GABRIEL STOKES spent his early years at Sligo, 
Ireland, and received his educational equipment at Cam- 
bridge University, where he distinguished himself so highly 
as a mathematician that he was elected in 1849 to fill the 


312 Beacon Lights of Science 


Leucanian chair there. He became president of the Royal 
Society in 1885. 

Stokes was the first to explain the basic principles upon 
which the science of spectroscopy rests, namely, that ab- 
sorption spectra and emission spectra are identical (a prin- 
ciple afterwards rediscovered by Kirchhoff), and published 
several very important papers on light and allied subjects. 

His great discovery, however, was that of the cause of 
the phenomena of fluorescence, about which, up to his time, 
practically nothing was known. His explanation may be 
stated as follows: 

All varieties of matter, when subjected to the action of 
a beam of sunlight, experience more or less of a rise in 
temperature. Some few are capable of absorbing the light 
rays almost as fast as they arrive, and exhibit mainly the 
transfer of that form of energy into motion; as, for in- 
stance, water, which, under the action of light, will show 
a slight increase of temperature it is true, but the principal 
effect is the change of some of it into the condition of a 
vapor, and the elevation of this into the air (evaporation). 
Other substances, as most solids, are unable to absorb light 
as rapidly as it reaches them. Some of these have the 
power to reflect nearly all of it, like good mirrors. Others 
absorb part, reflect part, and radiate the balance in the 
form of heat. Still another class possess the ability of 
absorbing the violet and ultra-violet (invisible) rays, with- 
out experiencing much of a rise of temperature, and then 
of returning the energy so absorbed in the shape of longer 
and visible rays of green, yellow and even pink. The 
mineral fluorspar possesses this power preeminently, and 
also certain liquids (quinine sulphate). This is the phe- 
nomenon called fluorescence. It is exhibited to a greater 
er less extent by a number of other familiar substances, 
ivory, dry bone, glass colored by uranium oxide (canary 
glass), and some varieties of paper. 

Most of these fluorescent substances cease to emit light as 
soon as the incident ray is cut off. Others, and notably 
barium, strontium and calcium sulphides, diamonds, sul- 
phur, sugar and many forms of animal life, retain the 


The Nineteenth and Twentieth Centuries 318 


power for some time afterwards. The phenomenon is then 
known as phosphorescence, but has nothing whatever to do 
with phosphorus. 

Stokes’ explanation has been abundantly demonstrated, 
and is known as Stokes’ law, which, in brief is: ‘‘That 
fluorescent light is of a longer wave length than that of the 
absorbed waves from which it is produced.’’ 

One of the results flowing from this discovery, is that a 
certain length of the ultra violet and invisible part of the 
solar spectrum, can be made visible, by throwing those rays 
upon a screen moistened with some fluorescent substance, 
which will then return them in the shape of rays of longer 
wave length, which produce in the eye the color effects we 
call green, yellow and pink. 


TYNDALL (1820-1893) 
PHYSICS 


JOHN TYNDALL was brought up at Leighlin Bridge, in 
Treland, received his primary education there, and at the 
age of twenty-four became a subordinate employee of the 
Ordinance Survey, and later of a firm of railroad engineers. 
In 1847 he went to England, and undertook the teaching 
of mathematics and surveying at Queenwood College at 
Stockbridge. After a year there he went to Marburg, 
Germany, and devoted a couple of years to study, return- 
ing to Queenwood in 1851. In 1852 he was elected to 
membership in the Royal Society, and largely as the result 
of his first paper read before it, on ‘‘ Molecular Influences,?? 
and the delivery of a lecture before the Royal Institution, 
on ‘‘The Transmission of Heat Through Organic Sub- 
stances,’’ he was offered the chair of natural philosophy. 
This brought him into intimate relations with Faraday, 
who was also a member of the faculty. In 1856 he studied 
the Swiss glaciers, in company with Huxley, climbed the 
Weisshorn in 1861, and the Matterhorn in 1868; traveled 
in Algeria in 1870, and lectured in the United States in 


314 Beacon Lights of Science 


1872. Upon the death of Faraday, in 1867, Tyndall suc- 
ceeded to his position in the Royal Institution, and also to 
his post as scientific adviser to the government, in connec- 
tion with the activities of Trinity House, which had charge 
of the Lighthouse Service. 

In addition to his great ability as an investigator and 
experimenter in the fields of science, he possessed unusual 
capacity and charm of manner as a lecturer, having the 
power of interesting his audiences in science to a remark- 
able degree. This faculty brought him large financial re- 
turns, wherever and whenever he was willing and able to 
accept engagements among English speaking people. No 
man of his time contributed as much to the spread of 
knowledge of nature among the masses. While none of 
his discoveries were of a startling nature, yet he made 
several of importance, and all have been since fully con- 
firmed. An example of these was his demonstration that 
in pure air, free from dust or germs, a beam of light is 
invisible, unless coming directly to the eye. This led to 
a recognition of the enormous amount of organic and inor- 
ganic impurities normally existing in the atmosphere, to 
a study of their character and effects, and to improvements 
in methods of sterilization, for the preservation of foods, 
the care of wounds, and the prevention of diseases of an 
infectional character. 

Tyndall, like Huxley, was popularly classified while liv- 
ing as a materialist. This mental attitude at the time was 
defined by the orthodox as ‘‘the denial of the existence in 
man of an immaterial substance which alone is conscious, 
distinet, and separate from the body,’’ and those who held 
it were assumed to be atheists. These two notable and 
reverent students of nature were, like their contemporaries, 
Darwin and Spencer, men of deep religious convictions, as 
anyone must be who makes a sincere study of any aspect 
of the Cosmos, and they properly resented the imputation 
of atheism. To counteract the unwarranted inference 
drawn by their critics, Huxley invented the word agnostic 
to express the attitude that he—together with most of the 
scientists of the time—took, Their school of thought, which 


The Nineteenth and Twentieth Centuries 315 


has spread enormously since, holds that human knowledge 
is limited by experience, and that since the Absolute and 
Unconditioned cannot fall within experience, we have no 
warrant in asserting anything whatever with regard to it. 


MULLER (1821-1897) 


BIOLOGY 


JOHANN FRIEDRICH THEODOR MULLER (known as Fritz 
Miiller), was born at Windischholzhausen in Germany, and 
studied at the schools of Griefswald and Berlin. To escape 
the political troubles of 1848, he emigrated to Brazil, locat- 
ing himself at Blumenau, on the island of Santa Catarina, 
where he lived the life of a colonist until 1856, when he 
became a teacher of mathematics and physics at the Gym- 
nasium at Desterro, the principal town of the island. In 
1874 he was appointed a traveling naturalist of the mu- 
seum at Rio Janeiro, with residence at Itajahy. From this 
position he was removed several years later, for political 
reasons, and returned to Blumenau. 

Miller became an intense advocate of the evolutionary 
theories advanced at the time by Darwin, and being an 
earnest and capable observer, and living in a place where 
he could study, with particular advantage, the marine 
crustacea, he made their investigation a specialty, and 
in 1864 published in Leipsie his one work entitled, ‘‘ Facts 
for Darwin,’’ in which he applied the Darwinian hypothe- 
ses to his years of research in that class of the division of 
the Arthropoda. This monograph won for him, not only 
the grateful acknowledgments of Darwin, but wide and 
well merited fame. In it, in the chapter on ‘‘Progress in 
Evolution,’’ he made the first clear and concise statement 
of the biogenetic law, as follows: 

‘‘That the embryonic development of the individual is 
an epitome of the order or class to which it belongs.’’ 

At the foundation of this broad generalization was the 
assumption—now universally accepted by biologists—that 
all living things have had a common ancestry, which is 


316 Beacon Lights of Science 


made clear by the fact that, in all those cases whose embry- 
ological development has been carefully studied, it has been 
found that the embryo passes through stages, or tem- 
porarily inherits structures, which are permanent in, and 
characteristic of, the more primitive or ancestral members 
of the class to which it belongs. 


HELMHOLTZ (1821-1894) 


PHYSICS 


HERMAN Lupwic FERDINAND VON HELMHOLTZ, a native of 
Potsdam in Prussia, was educated in Berlin as a physi- 
cian and surgeon, in which capacity he served in the 
army during the years 1843-47. At the close of the war 
he was appointed an assistant in the Berlin Anatomical 
museum, and filled in turn the chairs of physiology at the 
universities of Konigsberg, Bonn and Heidelberg in the 
years from 1849 to 1871. In the latter he was elected to 
the professorship of physics at the University of Berlin 
and continued in that office until his death. 

While not the discoverer of the principle of the Conser- 
vation of Energy, for which credit should be given to 
Joule; to Helmholtz rightly belongs the honor of establish- 
ing it on a firm and mathematical basis. In his monograph 
on the subject, entitled, ‘‘Ueber die Erhaltung der Kraft,’’ 
which appeared in 1847, he discussesd all the facts that 
had been made known to that date, by numerous experi- 
menters and investigators on the different varieties of force, 
and in a most masterly manner. This paper was at first 
considered by many as little better than a fantastic specu- 
lation, for it asserted the identity of motion, light, heat, 
electrical, magnetic and chemical action; but it was favor- 
ably regarded by such master minds as Rankin, Thomson 
(Lord Kelvin), Clausius, Maxwell, and others, and steadily 
won its way to acceptance because, being founded on dem- 
onstrated facts, it could not be logically disputed. 

Foree may be pictured in the mind, either as an effort 
made by something to do work, or as the inherent capacity 


The Nineteenth and Twentieth Centuries 817 


of matter to exert energy. The first conception was the 
one prevalent in the day of Newton, when mechanics was 
the only physical science of which enough was known to 
allow the investigation of its phenomena with the tool of 
mathematics. But when it became evident, through the 
experiments of Rumford, Davy and many others, that mo- 
tion could be transformed into heat, a new idea was 
launched among thinkers. However, it was not until 1845 
that Mayer made an experiment, from which he deduced 
a definite numerical value for the mechanical equivalent 
of heat. His figure was 365 gram-meters, and was de- 
rived by observing the heat evolved in compressing air. 
Joule, after investigating the thermal and chemical effects 
of an electrical current, deduced the figure of 460 gram- 
meters. Then, by utilizing the force of gravity as the 
source of energy, he obtained the value of 423 gram-meters. 
Next, a Danish engineer named Colding announced the 
figure of 370 as the result of heat caused by the friction of 
solid bodies on each other, thus harking back to the primi- 
tive method of producing fire, by rubbing two pieces of 
wood together. Joule, undaunted by these discordant re- 
sults, with indefatigable energy attacked the problem in 
several different ways, and finally announced in 1850 the 
figure of 423.55 gram-meters as his final conclusion. This 
stood, as aecepted tentatively, for more than 20 years. In 
that interval the problem was studied by numerous investi- 
gators in the fields of the electric, magnetic and chemical 
sciences, and in 1877-1879, as the result of exhaustive re- 
viewing experiments made by Professor Rowland at Balti- 
more, Md., the figure of 425.9 at 20 to 35 degrees centi- 
grade, was adopted. Expressed in plain language, this 
means that the energy required to lift a weight of 1 gram 
to a height of 425.9 meters, or a weight of 425.9 grams to 
a height of one meter, is exactly sufficient in that form of 
energy called heat, to raise one gram of water, one degree 
centigrade in temperature. 

In the days of Helmholtz, electricity, magnetism and 
light were still regarded, by all but a few, as subtle forms 
of matter, just as heat had been in the time of Joule; so 


318 Beacon Lights of Scrence 


it is not difficult to understand the revolution in thought 
required, to accept the idea that they, as well as all forms 
of chemical activity, were but different manifestations of 
that one form of force clearly comprehended under the 
name of motion. The fundamental principle is, that the 
total stock of energy in existence in the Universe is con- 
stant, that it is impossible to create or destroy it, and that 
all we can do is to change any one manifestation of it, 
into some other manifestation. 

It is interesting to note here that this principle has, for 
considerably more than a century, been held to be true for 
all manifestations of matter, which, unereatable and inde- 
structible, may be changed from one form or condition to 
another, without loss or increase in quantity. And finally, 
physicists now appear to have shown that the supposed 
ultimate forms of matter, the atoms, are probably simply 
centers of force. How much further the inquiry may be 
pushed, and what will be the ultimate conclusion, is impos- 
sible to say. 

Helmholtz discovered the principle of vortex motion. 
He developed the theory of Young on colors. His mono- 
graph on the ‘‘Sensations of Tone,’’ which appeared in 
1863, remained for many years thereafter as the most 
important work extant on acoustics. In 1883 he was ele- 
vated by the German Emperor into the nobility. 


VIRCHOW (1821-1902) 


PATHOLOGY 


RupDoLPH VircHOW was reared at Schivelbein in Prussia. 
He graduated in the medical department of the University 
of Berlin, and became professor of anatomy there. 

During the political disturbances of 1848-1849 in Prus- 
sia, he took a decided stand against the government, which 
cost him his position at the university, and led him to ac- 
cept the chair of pathological anatomy at the University 
of Wurtzburg in Bavaria, where his reputation as a lec- 
turer on his special subject—cellular pathology—became 


The Nineteenth and Twentieth Centuries 319 


so great, that in 1856 he was reealled to Berlin, and his 
political views overlooked. In return, he made its medical 
school the most famous in Europe during his lifetime. 

Retaining, with great independence, his position against. 
the encroachments by the royalists on the liberties of the 
people, he was elected in 1862 as a Deputy to the Prussian 
Diet, and at once rose to the position of leader of the 
opposition. During the Franco-Prussian War (1870-1871), 
and the events which followed, resulting in the formation 
of the German Empire under the leadership of Bismarck, 
he continued active in politics, as a leading member of the 
Fortschrittspartei, or Progressists; while at the same time 
retaining the respect of the imperialists, as well as his 
connection with the University of Berlin, where he ranked, 
up to the last, as the most famous pathologist in Europe. 

Before his time Pathology (the study of disease), was in 
no sense a science, that is, a classified collection of well 
demonstrated facts or phenomena. It was little more than 
a collection of theories, and guesses. Its remedies were 
drugs, whose chemical composition was unknown, and even 
the nature and action of foods were unexplained mysteries. 
It remained for Virchow to throw a strong—almost blind- 
ing—light on this darkness, by enunciating and demon- 
strating, such a conception of the constitution of the living 
body, as was fundamental in its character, and upon which 
as a basis, a rational system for the treatment of diseases 
of all kinds could be raised. This was the system of cellu- 
lar pathology, which is not difficult to understand as a 
whole. 

All parts of all organs, tissues, and liquids of the body, 
are either composed of cells, or are in part or wholly, the 
product of cells. This is the fundamental and demonstrated 
fact. The liquids of the body—as the blood—differ from 
the solider parts—as the flesh, bones, ete-——only in that 
they have fluid intercellular substance in their composition. 
Cells are the conductors or transporters of vital functions. 
The condition that we call health, is the result of normality 
in cell function; and that which we denominate disease, 
is due to cell functional abnormality. Whenever the latter 


320 Beacon Lights of Science 


state is apparent, as in fever, chill, pain, decay, ete., the 
ultimate cause is to be found in the cells of the deranged 
organ, tissue, or fluid, and the remedies indicated, are 
those which experience has shown will act upon those par- 
ticular cells, or upon the cellular system as a whole. 

Naturally, since Virchow’s time, pathology as a science 
has been much enlarged, extended, sub-divided and special- 
ized; but the basic principle upon which the structure of 
the medical art of the present day has been erected, re- 
mains as enunciated by him. 

The Pathological Institute and Museum at Berlin, erected 
by the German government in accordance with his designs, 
is his greatest material monument. At the time of his 
death it contained over 23,000 specimens, which have been 
more than doubled since. So great was his renown, and so 
immense the benefits that his work has conferred upon the 
world of suffermg humanity, that upon the occasion of 
the celebration of his 80th birthday by a complimentary 
dinner in Berlin, testimonial dinners were simultaneously 
held in many of the large cities of Europe and in several 
of those in the United States. 


GALTON (1822-1911) 
BIOLOGY AND PHYSICS 


FRANCIS GALTON was a native of Birmingham, England, 
and was educated at King’s College in London, and at 
Cambridge University. He was a man of many tastes in 
science with large experiences in many lines. In 1846 and 
1847 he traveled in Egypt. In 1850 he began explorations 
in South Africa, landing at Walfisch bay on the west coast, 
and spending two years in the interior, which was then 
known as Demerara Land; where he discovered the Ovampo 
tribe of natives, a very interesting branch of the Bantu 
race of Africa which had become completely separated 
from the rest of their people and consequently developed 
different customs and habits. He published two books on 


The Nineteenth and Twentieth Centuries 321 


the subject of his travels in the Dark Continent, and hav- 
ing become interested there in meteorology he published in 
1863 his ‘‘Meteorographica,’’ in which he cutlined for the 
first time the theory of anti-cyclones, which has since be- 
come one of the fundamental principles of present day 
weather forecasting. 

His attention then being turned to anthropology he be- 
came a voluminous writer on the subject, publishing in 
1869 ‘‘Hereditary Genius’’; in 1874 ‘‘Englishmen of Sci- 
ence’’; in 1883 ‘‘Inquiry into Human Faculty’’; in 1889 
‘Natural Inheritance’’; in 1892 ‘‘Finger Prints’’ and 
‘“TIndex of Finger Prints’’; and finally, ‘‘Law of Ancestral 
Inheritance.’’ He is regarded as the great authority on 
the subject of human heredity, having put that science on 
a quantitative basis. 

Galton also called attention, in his ‘‘Meteorographica,’’ 
to the phenomena of atmospheric displacement and storms. 
He showed that dense air is warmer than normal air, and 
will hold in suspension in the form of vapor a higher 
percentage of water; that is to say, its degree of humidity 
is greater. As it expands it becomes cooler, loses a meas- 
ure of this capacity, and precipitates more or less of the 
moisture it contains in the form of rain, hail or snow in 
parts or all of the surrounding region. 


WALLACE (1822-1905) 


NATURAL HISTORY 


ALFRED RUSSEL WALLACE was born at Usk, in the south- 
west of England near the border of Wales, and began his 
active life as a surveyor and engineer. For a short time he 
was Master in English in the Collegiate School at Leicester, 
where he became interested in botany and entomology. 
When Darwin’s first book—‘‘The Voyage of a Naturalist”’ 
—appeared, it attracted him so strongly that, with the 
naturalist Bates as an associate, he sailed early in 1848 for 
Brazil, the two planning to explore the Amazon valley. 
Shortly after leaving Para, at the mouth of the river, 


B22 Beacon Lights of Science 


they parted company under a friendly agreement, Wallace 
taking as his field the country on the north side of the 
great stream, while Bates confined himself to that on the 
south. 

Wallace followed the river to the mouth of the Negro, 
its main northern affluent, and traced the latter to its source 
in the great upland region of southeastern Colombia. Here 
he discovered the curious fact that its upper waters were at 
one place identical with those of the Orinoco. The fact is, 
that at a point about 150 miles below the main southern 
source of the Orinoco, and at an altitude about 1000 feet 
above the level of the sea, the stream forks, about one-sixth 
of its waters passing south through the Cassiquiare and 
thence into the Negro, and the remainder north, thus mak- 
ing it possible without portage except at the Atures and 
Maypures rapids on the Orinoco, to travel by boat of light 
draught from the mouth of one river to that of the other. 

Wallace made a fine collection, but had the misfortune 
to lose it, as well as all his notes, by shipwreck, on his 
return trip to England. Nevertheless he published in 1853 
a highly interesting and valuable account of the country 
through which he had journeyed. In the following year 
he went to the East Indies, and explored them from the 
peninsula of Malacca through Sumatra, Java, Borneo, the 
Celebes and the islands of the Banda sea to, and some 
distance into, New Guinea, devoting eight years to the trip, 
and finding himself more interested in ethnology and 
philology than in plant and insect life. 

During a period of resting and recuperation at Sarawak 
in Borneo, he wrote an essay entitled ‘‘The Law which has 
Regulated the Introduction of New Species,’’ which was 
published in 1855. But in it he went no farther than to 
deny that species were matters of special creation, and 
to assert that they were the result of slow and gradual 
development from one to the other, in accordance with 
some law as yet not understood. Somewhat later, having 
meantime read the work of Malthus on ‘‘Population,’’ the 
reasons advanced by that economist to account for varia- 
tions in number, and changes of character, in races of men 


The Nineteenth and Twentieth Centuries 323 


and in nations, seemed so suggestive when applied to ani- 
mal life in general (just as it had to Darwin who, however, 
had read it twenty years before), that he at once wrote 
another essay entitled ‘‘On the Tendency of Varieties to 
Depart from the Original Type,’’ and sent it to Darwin, 
who was a personal friend. It arrived just at the time 
when the latter had arranged to read before the Linnaen 
Society his own preliminary paper on the subject, in which 
he presented substantially the same cause—though much 
more completely in detail—as an explanation of variation 
and mutation in species. It was an embarrassing situation, 
and to his great credit it should be remembered that Dar- 
win offered to suppress his paper in favor of that of Wal- 
lace. But those who were close to him, and who knew that 
his conclusions had been reached independently, and after 
years of investigation, dissuaded him from such a course, 
The upshot was that both essays were read at the meeting, 
and printed in the Transactions for that year (1858), and 
in the following year Darwin’s great work, ‘‘The Origin 
of Species,’’ appeared. 

As a result of his long and extensive travels in the far 
east, Wallace published several works of high value on the 
natural history of that part of the world. These gaine 
for him a government pension sufficiently liberal to eng 
him to pass the rest of his life at home in comfort., 
was a man of lofty personal character, and of an am 
and genial disposition. The long friendship between * 
win and himself was never interrupted. On the contrary, 
he admitted frankly that he had arrived at his conclusion 
almost entirely by accident, while Darwin had reached his 
only after years of patient observation and experimenta- 
tion, and was unquestionably entitled to the greater credit. 

The idea of evolution is a very old one. It was current 
and practically accepted in the golden age of Greece, but 
the cause of it’ was not even dimly suspected by the phi- 
losophers of the time. During the centuries that followed 
their eclipse, and all through the Dark Ages, the orthodox 
theory of a special Creation was received in Europe with- 
out question. When Lamarck (1744-1829) ventured to 








324 Beacon Lights of Science 


doubt it, and reasserted the older idea, the causes he as- 
signed for it—changes of environment, climate, soil, food, 
temperature and_ cross-breeding, seemed inadequate. 
Cuvier himself would not accept them. And though 
Lamarck briefly touched on the competition for food as a 
factor, he evidently regarded it as a minor one, while for 
Malthus it was the principal one. The uneritical but alert 
Wallace seized on it as an inspiration, and without further 
study adopted it. Darwin, however, devoted nearly a score 
of years to its study, before announcing it as a conclusion 
that could be amply proved. 


MENDEL (1822-1884) 


BIOLOGY 


GEORGE JOMANN MrNvDEL was a native of Heinzendorf in 
Austria, was edugated far the ministry, and became a 
priest in 1847. While faithfully performing the duties of 
his office he found time, in the garden of the cloister, to 
become deeply interested in botany, and particularly in that 
department of plant life which includes those variations 
sulting from cross-breeding among different varieties, 
ies or genera. After nearly twenty years of patient 
7 and experimentation, his great work ou the subject 
ared in 1865 under the title of ‘‘ Versuche tiber Pflan- 
briden.’’ In this he summarized his conclusions into 
what has come to be known as Mendel’s law which, in ef- 
fect, may be stated as follows: 

‘In the second and later generations of a hybrid, every 
possible combination of the parent characteristics occur, 
and each combination appears in a definite proportion of 
the individuals. A parent character which is fully devel- 
oped in the hybrid is said to be ‘dominant’; if it is appar- 
ently absent it is said to be ‘recessive.’ ”’ 

This law has been expressed in more detail by Castle, 
thus: 

‘*1. The law of dominance ; when, for example, in the off- 
spring of two parents differing in respect of one character, 







The Nineteenth and Twentieth Centuries 325 


all resemble one parent, and possess therefore the dominant 
character, that of the other parent being latent or recessive. 

‘<2. In place of simple dominance, there may be manifest 
in the immediate hybrid offspring an intensification of 
character, or a condition intermediate between the two 
parents; or the offspring may have a peculiar character of 
their own, technically known as ‘heterozygotes.’ 

‘3. A segregation of characters united in the hybrid takes 
place in their offspring, so that a certain per cent of these 
possess the dominant character alone, a certain per cent 
the recessive character alone, while a certain per cent are 
again hybrid, that is, possessing the characteristics of both 
parents.”’ 

Mendel’s law attracted little attention at the time of its 
publieation, but after thirty-five years of obscurity it was 
rediscovered by biologists and amply confirmed. But even 
before his pioneering labors had been recognized among 
scientists men like Burbank of California had experimented 
deeply on the subject, and produced remarkable results in 
plant life, and others in poultry and the domestic animal, 
so that at the present time the ability to bring about very 
extensive changes in both, and changes that can be pre- 
dicted, is well demonstrated. It is safe to expect that in 
the not very distant future the discoveries in this branch 
of knowledge will be extended to the improvement physi- 
eally and mentally of man. The science of eugenics is 
young but vigorous, and a very firm foundation has al- 
ready been laid upon which to build. 


CLAUSIUS (1822-1888) 


PHYSICS 


Rupo.F JuLIUS EMANUEL CLAUSIUS was a native of Kés- 
lin, in Germany, was well educated, and became in turn 
professor of physics at the polytechnic institute at Zurich 
(1855), in the University of Wurtzburg (1867), and in the 
Bonn University (1869). He remained at the last until 
his retirement. 


326 Beacon Lights of Science 


He was one of the founders of the comparatively mod- 
ern science of thermodynamics, having, in a monograph 
read in 1850, before the Berlin Academy of Sciences, enun- 
ciated and demonstrated its second law, to the effect that 
‘‘heat cannot itself pass from a colder to a hotter body.’’ 

Among the Greek philosophers, heat effects were believed 
to be due to the addition of a material substance to the 
body experiencing a rise of temperature. This conception 
was universally held until about the year 1800. In fact, 
somewhere about 1696, a Professor Stahl, of the Univer- 
sity of Halle, in Germany, gave the assumed substance a 
name—phlogiston. Another name familiarly employed 
somewhat later for the same imaginary thing was ‘‘cal- 
oric.’? And though during the 17th and 18th centuries 
(1600-1800) certain of the philosophers of the time— 
among whom may be mentioned Descartes, Amontons, 
Boyle, Francis Bacon, Hooke and Newton—demurred at 
this view, and expressed the opinion that it must be some- 
thing different, and probably was some form of motion, yet 
they were unable to furnish proof sufficient to discredit 
the popular conception current. It remained for Count 
Rumford, towards the end of the 18th century, to furnish 
the necessary evidence. Yet, millenniums before that, our 
savage ancestors had learned that fire could be produced 
by rubbing two pieces of wood together. 

It is now known that all heat phenomena can be traced 
for their cause, to work of some kind having been done 
against the molecular forces of the body, by friction, com- 
pression, or the reception of energy by radiation, conduc- 
tion or convection. In other words temperature is simply 
a question of molecular motion. As matter loses heat the 
motion of its molecules slows down, and at the absolute 
zero ceases entirely. As heat is acquired, molecular mo- 
tion increases, leading first, in the case of most substances, 
to the change from a solid to a liquid state, and then from 
a liquid to that of a gas. 


The Nineteenth and Twentieth Centuries 327 


PASTEUR (1822-1895) 


BACTERIOLOGY 


Louis PastEeur spent his adolesence at Dole, among the 
foothills of the Jura mountains in eastern France. At an 
early age he developed a strong interest in the sciences, par- 
ticularly chemistry and medicine. He secured his doctor’s 
degree at twenty-five, and at once became professor of 
physics at the University of Dijon. After a year there, he 
was offered and accepted the chair of chemistry at the Uni- 
versity of Strassburg. In 1854 he became dean of the 
Faculty of Sciences of the State university at Lille. Three 
years later he took the post of science director at the Ecole 
Normale Supérieur, in Paris, and was elected a member of 
the French Institute of Arts and Sciences. In 1863 he was 
appointed professor of physics and chemistry at the school 
of fine arts, and from 1867 to 1875 occupied the chair of 
chemistry at the Sorbonne, one of the departments of the 
University of Paris. A little later he founded, and con- 
ducted during the balance of his active life, the Pasteur 
Institute; which became at once a very famous center of 
research in his particular line of investigation. 

Pasteur is regarded as the originator of the science of 
stereo-chemistry, which has for its field the investigation 
of those substances of the isomeric category, which cannot 
be explained by the linking of their constituent atoms, but 
are explained on the theory that their combining powers act 
in certain definite direction, in space. This naturally leads 
up to the study of the phenomena of fermentation and 
putrefaction, and their relation to the micro-organisms in 
the atmosphere. By passing a current of air through gun- 
cotton, and then dissolving the latter in alcohol, an insol- 
uble residue is obtained which, under the microscope, is 
found to consist largely of mature and immature -living 
germs. 

The study of these—a hitherto unknown field of life— 
occupied the remainder of Pasteur’s days. The discoveries 
made therein by him, and by those who have followed in 


328 Beacon Lights of Science 


his steps, have profoundly affected individual humanity, 
and the industrial world. To mention a few of the most 
important will indicate the scope of his labors, and the 
gain that has resulted from them. His investigation of 
the diseases of wine and beer have made it possible to 
prevent them. The same has occurred in the case of the 
silkworm disease. In discovering the bacterial cause of 
anthrax and splenic apoplexy in cattle, and of fowl chol- 
era, and the remedies in each case, enormous annual losses 
in domestic animals has been prevented, and a system of 
animal vaccination worked out, which has already done as 
much for the eradication of these diseases, as Jenner’s dis- 
covery has in the case of smallpox. Nor should his well 
known and very successful treatment for hydrophobia be 
forgotten; nor the system of sterilization which is now 
universally adopted in the modern dairy. In fact, so 
numerous were the discoveries of this most noted physi- 
ologist in the domain of the micro-organisms, and so suc- 
cessful the remedies he devised to defeat or minimize their 
injurious action, that the terms pasteurizing, pasteurism 
and pasteurization as nouns, and the verb to pasteurize, 
together with similar words in all the modern languages of 
civilized people, have passed into common usage, to mean 
all preventative or prophylactic systems devised, either by 
him or since his time, to counteract the evil effects of those 
minute organisms which are always present in the purest 
air and the cleanest environment, and are every ready to 
attack and destroy. 


LEIDY (1823-1891) 


NATURAL HISTORY 


JosePH LeIpy was born in Philadelphia, Pa., and gradu- 
ated in 1844 at the State University with the degree of 
M.D. But becoming at once more interested in natural 
history than in the practice of medicine, he was appointed 
in 1846 curator of the Academy of Natural Sciences, and 
a little later demonstrator of anatomy at his alma mater. 


The Nineteenth and Twentieth Centuries 329 


Six years afterwards he became full professor of anatomy 
there, and in 1882 professor of biology. In 1885 he was 
elected president of the Wagner Free Institute of Science 
in Philadelphia. In 1844, for distinguished contributions 
to the science of paleontology, he was awarded the Lyell 
medal of the Royal Geological Society of London, and in 
1888 the Cuvier medal of the Institute of France. 

He will be remembered largely in connection with the 
fossil history of the horse and camel, in the study of which 
he was associated with Marsh. Their field of exploration 
was those remarkable fossil beds in Wyoming and western 
Nebraska which yielded such an abundance of the re- 
mains of the two animals as to make it possible to trace 
their ancestry in the remote past, and their development 
up to the forms known at the present day. 

The conclusion reached by Leidy was that the camel 
arose in early Tertiary time, contemporaneously with the 
pig family, and perhaps from common ancestry, and that 
the place of its origin was the ancient lake region of the 
Rocky Mountains. This was at first a well watered and 
even marshy country, but later became desiccated. Diminu- 
tive remains suggesting the camel have been found in the 
lower Eocene division of the Tertiary, and in the upper 
Eocene skeletons undoubtedly cameloid. These latter were 
about the size of a jackrabbit. They had four toes but 
used only two of them. Their dentition exhibited strong 
similarities to both the swine and camel type. In the up- 
per Eocene was found the procamelus, as large as a sheep, 
and presenting many points of likeness to the llama of 
the present day as found only in South America. As the 
aridity of the region increased the large splayed feet with 
sole pads were shown in the skeletons found. At the close 
of the Miocene the climate again changed, becoming warmer 
and moister. This seems to have put an end to camel life 
in North America, for no further remains of the type have 
been found. It was the belief of Leidy that an emigration 
then took place of the existing type, some going to the 
south and becoming the ancestors of the three or four 
varieties now living in the highlands of the Andes, and 


330 Beacon Lnghts of Science 


others to the northwest, via the land bridge at Behring 
straits into Asia where, in the arid regions of Mongolia 
the double-humped Bactrian camel was evolved, and from 
it later the single-humped variety known as the Arabian 
camel. 

The modern camel is a most remarkable case of adapta- 
tion to environment. The foot consists of two elongated 
toes, each tipped with a small nail-like hoof. The leg does 
not rest on this hoof but on the elastic pads or cushions 
under and back of them. In the Asiatic variety the toes 
are united by a common sole, thus presenting one broad 
pad for support on the loose sand of the desert. The thigh 
bone is unusually long, and the hind leg lacks that power- 
ful muscular connection with the barrel of the animal which 
is So prominent a feature in the anatomy of the horse. In 
fact, the leg is almost disconnected from the body. In 
consequence, if the sand under a rear foot of a camel gives 
away, his body is not dragged down with it as that of a 
horse would be, unless the other foot also is undermined. 
Still more wonderful as an adaptation is the stomach. The 
camel is a ruminant and chews the eud. Like all others 
of this order the digestive organ is divided into four parts 
or chambers. Two of these in the camel are connected by 
separate passages with the mouth, into one of which the 
animal sends the solid food it gathers in the field, and into 
the other the water it drinks, though it has also the power 
to pass water into either at will. Both of these divisions 
of the stomach (but principally the one to which liquid 
food is generally sent) are provided with a number of 
pouches or cells in their linings, with muscular walls, and 
with orifices that can be opened or closed as desired. When 
water is available in plenty these are all filled to distention, 
and when the liquid is needed it is allowed to exude and 
mingle with the solid food, until enough has been provided 
for the time being for digestive and other bodily functions. 
By this arrangement a camel can live and travel without 
too serious discomfort for from five to seven days without 
drinking. 


The Nineteenth and Twentieth Centuries 331 


FABRE (1823-1915) 


NATURAL HISTORY 


JEAN Henri Casimir FAsre was born at Sainte Leons in 
the south of France, the son of a small land owner with a 
family so large and an income so meager from his little 
patch of earth, that it became necessary at a very early age 
to send him to his grandparents in the neighboring village 
of Malaval where, by tending the geese and the ducks he 
could at least earn his keep. But when seven years old 
conditions at home being slightly improved, he was brought 
back and sent to the local primary school. In 1833 the fam- 
ily left their little farm and moved to the town of Rodez, 
where the father opened a café and the boy was able to 
attend school, where he made good progress. By this time 
his inclinations towards the study of natural history had 
become so strongly developed that the Latin he was forced 
unwillingly to study became a fascinating task as soon as 
he had advanced far enough to encounter the ‘‘Bucolics’’ 
of Virgil. Four years later the family moved again, to 
Toulouse, and in the following year to Montpellier. Jean 
was now a sturdy lad of fifteen, and felt under obligations 
to leave his home and earn his living wherever he could find 
employment. Being a companionable youth he made friends 
everywhere, and the outdoor life of a laborer brought him 
continually in contact with the nature he loved. Work- 
ing conscientiously at every employment he secured, living 
simply, and saving his surplus earnings; when in his wan- 
derings he reached the city of Avignon, and learned that 
at its normal school there was to be held an examination 
for a bursary, he boldly entered the race and won it with 
ease. This good fortune enabled him to abandon manual 
labor and take the full course that the institution provided. 
When he passed his final examinations in 1843 with credit 
and before he had attained his majority, he was offered the 
position of teacher at the primary school connected with 
the college in the town of Carpentras. There he taught 
with such success, while at the same time grasping every 


332 Beacon Lights of Science 


opportunity to increase his own stock of knowledge, that 
he was offered the professorship of physics, mathematics 
and chemistry at the Lyceum at Ajaccio, on the island of 
Sardinia. While serving there he had the good fortune 
to meet the botanist, Moquin-Tandon, and to be able to 
assist him in his work of collection in the wonderful flora 
of that island. Between them a strong and lasting friend- 
ship developed. 

In 1852, in consequence of an attack of the malarial 
fever prevalent there in certain seasons of the year, Fabre 
decided to return to France, and through the aid of this 
friend was appointed to the professorship in physics and 
ehemistry at the Avignon lyceum where formerly he had 
been a student. There, in a region thronging with insect 
and bird life he passed several comparatively happy years, 
devoting his leisure hours to investigations in natural his- 
tory and chemistry. 

By this time he had become so well known among scien- 
tists by his frequent small publications and contributions to 
current periodicals that he was elected a member of the 
Legion of Honor. In 1858 he won his degree as licentiate 
in natural history, and a little later the coveted doctor’s 
degree, which he hoped would open to him a eall to a 
university position. This not coming because, as he learned 
afterwards through a friend, of his limited means, he be- 
gan the investigation of the coloring matter alizarin, with 
the intent of undertaking the business of dyeing as a 
means of making money. But just as he was getting well 
started the era of synthetic dyes began, with which he 
was unable to contend. Thus at last Fabre was compelled 
to take to his pen seriously as a means of support. He had 
already published a few school text books, but they added 
little to his income. In 1870 he moved to a house in the 
suburbs of Orange where, surrounded by his devoted fam- 
ily, and far away from the world of strife, he spent nine 
happy years studying and describing the abundant insect 
life of the region, and easily finding a market for his work 
at fair remuneration. These monographs were written in 
a style at once so simple, and yet so delightful, as to win 


The Nineteenth and Twentieth Centuries 333 


for him a large circle of readers not only in France but 
throughout Europe and in America. Before he could 
fairly appreciate the fact he had become one of the most 
noted of naturalists. 

After the death of his eldest son Jules in 1879—a severe 
bereavement—he moved to a still more secluded residence 
near the little village of Serignan, where the balance of 
his long life was passed. There he planned and executed 
his great ten-volume work which made his name famous. 
It was published under the title of ‘‘Souvenirs Entomolo- 
giques.’’ In its composition he studiously avoided what 
he ealled the ‘‘official jargon’’ of science, adopting in its 
stead, and without the least sacrifice of accuracy, a style 
so charming as to bring his descriptions within the mental 
erasp of anyone who can read. No writer in his field since 
the far-off day of Virgil—who described so delightfully 
the life and doings of the bee, the grasshopper and the 
erow—has been able to convey to the masses so much, and 
so truthfully of the wonders of the world of small animate 
nature, in which he says he found a knowledge of Deity. 
Fabre, who was not what is called by theologians a religious 
man, was asked in his old age if he believed in God. His 
reply was—‘‘T can’t say I believe in him;I see him. With- 
out him I understand nothing. You could take my skin 
from me more easily than my faith in God.’’ 

The most important strictly scientific result that was 
reached by his life studies was undoubtedly the light that 
he threw upon the nature of the faculty of instinct, as con- 
trasted with that human one called reason. In his own 
words he regarded the former as proving, in the ease of 
each individual studied ‘‘ perfect wisdom, comparable with 
and even superior to human wisdom, within the customary 
conditions of their lives; and incredible stupidity outside 
of them.’’ This is perhaps the most correct definition of 
the character and nature of instinct as a phenomenon that 
has been put into words. 


334 Beacon Lights of Science 


HITTORF (1824- ? ) 


PHYSICS 


JOHANN WILHELM HITTORF was a native of Bonn in Ger- 
many, received his education at the university in that city 
and in 1852 became the professor of chemistry in the Uni- 
versity of Muenster, where he at once displayed his ability in 
original research. His investigations were mainly in the field 
of electricity, the earliest being on the phenomena of electrol- 
ysis, where he extended the work of Faraday in determining 
the mobility of ions of different substances in an electrolyte. 
In 1862, in collaboration with Plucker, the important dis- 
covery was made that the spectra of all substances differed 
materially under different conditions of temperature. In 
1869, while investigating the passage of the electrical eur- 
rent through glass tubes containing a rarefied gas, he ob- 
served that by increasing the degree of exhaustion the 
dark space between the negative pole and the negative 
glow widened, and that fluorescence appeared when the dis- 
charge from the cathode impinged on the wall of the tube; 
and he further found that all these rays could be deflected 
by the magnet, thus anticipating the brilliant demonstra- 
tions on this phenomenon that were made by Crookes in 
1878. Finally, in the field of chemistry, he was the dis- 
coverer of several hitherto unknown properties of phos- 
phorus and selenium. 

These two elements, which lie some distance apart in the 
Periodic system of Mendeleef, possess properties which, 
beside being of high interest, have made them useful in 
certain directions in the arts. Phosphorus was first en- 
countered as a hitherto unknown substance by Brand, a 
German alchemist, in 1669. He was working in his labora- 
tory on urine, striving to extract from it some principle 
or material that would effect the transformation of lead 
or copper into silver or gold which, in his day, was the 
principal end sought by all the devotees of what was called 
the ‘‘black art.’’ Brand did not recognize his find as 
an elementary body, but in some way he managed to iso- 


The Nineteenth and Twentieth Centuries 335 


late considerable of it crudely from the other elements with 
which it was associated—mainly nitrogen and hydrogen in 
the form of ammonia, and magnesia—in the sediment from 
urine, into which it had come from the bones, the nerves, 
the brain substance, the blood and other of the body fluids, 
where it is a normal and necessary constituent, and one 
which must be taken into the body in food if the organism 
is to be properly nourished. Accordingly it is found in 
all kinds of plant life, and in the flesh of all animal, par- 
ticularly fishes. Finally, it is always present in greater or 
less proportion in the soil, and in both fresh and salt water, 
the ultimate source being of course the rocks, where it 
occurs as phosphates combined with several of the common 
elements, but mainly with lime and magnesia. Brand ex- 
ploited some of its remarkable properties, and about a cen- 
tury later the chemist Lavoisier demonstrated its elemen- 
tary character. It is ranked as a non-metal, may be either 
red, yellow or black in color, crystalline or amorphous in 
structure, odorless, or with a distinctive odor, opaque or 
transparent, and must be kept under water free from air 
or will rapidly combine with oxygen and become phos- 
phoriec acid. It begins to melt and vaporize at 215 to 300 
degrees Centigrade, and will catch fire and burn fiercely 
with an intense white light if given the slightest opportun- 
ity. No wonder Brand was able to amuse himself and 
astonish others with a material having such unusual prop- 
erties. Until recent years practically all consumed in the 
arts has been produced from bones, but an increasing pro- 
portion is now coming from the rocks, of which enormous 
deposits have been discovered in various parts of the 
world. 

Selenium waz isolated and recognized as an element in 
1817 by the chemist Berzelius. It is widely distributed in 
the material of the earth’s crust, but in minute quantities. 
A very small percentage is found almost always in the ores 
of the metals copper, lead, silver, mercury and iron. When 
these are roasted preparatory to smelting, or during the 
latter process, the selenium passes away as a vapor, and 
when cooled settles down as a fine dust in the flue cham- 


336 Beacon Lights of Scrence 


bers with other easily vaporizable substances, from which 
it may be separated and recovered without difficulty. As 
with phospohorus, it ean exist in several different allotropic 
conditions, in one of which it appears as a black, glossy and 
metallic looking mass, but lacking the other metallic pecul- 
iarities. If heated in air it begins to soften at 60 degrees 
Centigrade, and at 250 dgerees passes into a very mobile 
liquid. If the temperature continues to rise it shortly 
bursts into a lovely purple flaming vapor, which gives off 
the odor of horseradish. The crystalline variety of the 
element has the unusual quality of becoming instantly an 
active conductor of the electric current when exposed to 
sunlight rich in red rays, and of losing that property with 
equal rapidity when the light is removed. This property 
is now utilized in the transmission of pictures or writing 
by wire, a feat which no doubt will ultimately be accom- 
plished as well by wireless. 


KIRCHHOFF (1824-1887) 


PHYSICS 


Gustav Ropert KIRCHHOFF was resident at Konigsburg, 
in Germany, and completed his education at the university 
in that city. In 1850 he became professor of physics at 
the University of Breslau, in 1854 at Heidelberg, and from 
1875 until his death he occupied the chair of that science 
at the University of Berlin. 

Tn addition to being regarded, with Bunsen, as a founder 
of the science of spectroscopy, he was the discoverer of two 
of the elementary laws of electricity, which may be stated 
in brief as follows: 

1.—At any junction point in a network of conductors, 
the sum of all the currents which flow towards that june- 
tion, is equal to the sum of all the currents which flow 
away from it. 

2.—In any complete electric circuit, the sum of all the 
electromotive forces, reckoned in order around the circuit, 
is equal to the sum of the products of the current through, 


The Nineteenth and Twentieth Centuries 337 


and the resistance of, each conductor forming the circuit. 

The germ of the science of electricity was probably the 
discovery that amber, upon being rubbed, acquired the 
property of attracting certain light bodies to it. This 
substance is a fossil resin of vegetable origin, differing 
in that respect from ambergris, which is of animal origin. 
Its golden color, its transparency and the pleasant fra- 
grance it gave off when burned, added to its comparative 
rarity, caused it to be highly valued by the ancients. It 
is thought that Thales of Miletus was among the first to 
become aware of its electrical capacity; and certainly 
Theophrastus knew of it for, in his treatise on Gems—to 
which category amber belonged in his day—he speaks of 
other substance as well as of it which possessed the mys- 
terious power of attraction. 


THOMSON (Lord Kelvin) (1824-1907) 


PHYSICS 


WituiAM THOMSON (later Lord Kelvin) was born at Bel- 
fast, Ireland, and graduated in 1845 at Cambridge with 
high honors. In the following year he became professor of 
natural philosophy at the University of Glasgow, a position 
which he retained for fifty-three years, until his retirement 
from active life in 1899. 

During his long career at this institution he was a volumi- 
nous contributor to the best technical periodicals of the 
day, and the inventor of a number of devices of great value 
in the operation of submarine telegraph cables, as well as 
a keen investigator in many other departments of physies. 
His most notable contribution to the increase of knowledge 
was in the field of thermodynamics. He was the first 
among his contemporaries to hark back to the doctrine of. 
the Conservation of Energy as advanced by Joule in 1847, 
and lightly regarded at the time, and to proclaim its funda- 
mental accuracy and importance. He also recalled to 
notice the brilliant essay of Sadi-Carnot on heat, published 
in 1820, and showed that it was, in effect, entirely in har- 


338 Beacon Lights of Science 


mony with that theory. His notable monograph, entitled 
‘““On an Absolute Thermometric Scale,’’ is rated as one 
of the classical documents in its line. 

In his investigations of the phenomena of electricity and 
vortex motion, he made some remarkable discoveries. In the 
latter, he advanced for consideration an ingenious theory 
of vortex action, as a possible explanation of the properties 
of the hypothetical ether of space, which aroused great 
interest at the time among mathematicians and physicists, 
but was not found competent to explain satisfactorily all 
the admitted properties of that assumed substance. 

He lectured in America in 1884, in 1897, and again in 
1902, on each occasion visiting several of the principal cities 
of the United States and Canada, and always drawing 
large and appreciative audiences. In recognition of his 
great services to the telegraphic art, he was knighted in 
1866, and raised to the peerage in 1902. 

The absolute zero of temperature has been determined 
by the properties of gases to be at —273.04° C., which cor- 
responds to —491° on the Fahrenheit scale. At this point 
all motion on the part of the molecule of matter is believed 
to cease, as the phenomenon called heat is, by definition, 
the effect produced by inter-molecular vibration. Lord 
Kelvin’s contention was that all statements of temperature 
should begin with this zero, that the freezing point of 
water should be 273° on the centigrade scale, and its boil- 
ing point 373°, instead of respectively 0° and 100° as at 
present. From a purely scientific point of view no dissent 
from this suggestion is possible. But the task of changing 
the thermometric scales of the whole world, as well as the 
popular conceptions of heat, has been found to be too great 
an obstacle to overcome. In consequence, the freezing point 
of water still constitutes the zero of the centigrade system, 
and 32° below that point as the zero of the Fahrenheit. 
In both of them the temperatures below that are stated as 
minus quantities in degrees. In practice, the nearest ap- 
proach to date to the absolute zero was reached at the 
solidification of hydrogen gas by Dewar at minus 256° C. 


The Nineteenth and Twentieth Centuries 339 


BROCA (1824-1880) 


ANATOMY 


Paunt Broca was a native of Sainte-Foy-la-Grande, a 
small town near the city of Bordeaux, France. Exhibiting 
in his youth strong inclinations towards medicine and sur- 
gery, he was given an excellent education in these sciences 
in Paris, which was supplemented by extensive hospital 
experience. At the age of twenty-three he began to be in- 
terested in anthropology, and in 1859 founded the Anthro- 
pological Society of Paris. This organization, which was 
officially incorporated a couple of years later, marked the 
beginning of that study as a distinct and very important 
branch of modern science, and to its growth and advance- 
ment Broca was a large contributor. In 1872 he established 
the ‘‘Revue d’Anthropologie,’’ in which for some time all 
his writings on that subject appeared. In 1876 he founded 
in Paris the Ecole d’Anthropologie, which is now known 
as the Anthropological Institute. It was well equipped 
with a library, museum and laboratory, and in the latter, 
Broca began those researches on the comparative anatomy 
of the primates, which led to the disclosure that has made 
his name memorable. In 1861 he announced his discovery 
of the location in the human brain, of the ganglion govern- 
ing the faculty of speech, as being situated (for right- 
handed individuals) in the third convolution of the left 
frontal lobe, and for left-handed individuals in the same 
convolution of the right frontal lobe. This particular part 
of the brain is now universally referred to as Broca’s con- 
volution and its recognition has had a most remarkable 
effect. It is a development of gray matter not found in the 
brain of any of the anthropoid apes, nor in that of the 
lower animals. Nor does it exist in the brain of the human 
infant, but comes into being only when the child begins to 
learn to speak. It develops only in one of the two major 
lebes of the brain, and usually in the left lobe, because all 
but an insignificant number of individuals are more dex- 
terous with the right hand than with the left. But in the 


340 Beacon Lights of Science 


ease of those who are left-handed from infancy, the speech 
ganglion appears in the opposite lobe. In cases of ambi- 
dextry, which are extremely rare, and never have been 
known to present a ease of perfectly equal capability with 
both hands, the development comes in that lobe opposite to 
the hand most employed. When the dexterous member is 
destroyed by accident, or in war, and ability to use the 
other is slowly acquired, the result is not the formation of 
a new speech center in the other brain lobe, nor any dis- 
ability in the power of speech. 

The effect of Broca’s discovery has extended beyond the 
fields of anatomy and anthropology, into that of psychol- 
ogy. In that most interesting and valuable work entitled 
‘‘Brain and Personality’’ the two sciences of physiology 
and psychology have been connected by means of the bridge 
revealed by him. 

He was a man of unusually varied talents. His statue 
by Choppin, was unveiled in 1887, in the Ecole de Mede- 
cine in Paris. 


HUGGINS (1824-1910) 


ASTRONOMY 


WILLIAM Huaains was a native of London, and received 
a thorough academic and collegiate education. Inheriting 
ample means, and having a strong inclination towards 
astronomical research, he built an observatory close to his 
residence, in which he mounted an 8-inch reflecting tele- 
scope. With this he continued during his life to make 
observations in great number, and of unusual value to the 
science, in spite of the adverse weather conditions so preva- 
lent in the vicinity of every large city. He was among the 
pioneers in using the spectroscope in connection with the 
telescope, and specialized on the study of the light coming 
to his instrument, from the celestial bodies. He was the 
first to detect that the spectra of some of the nebulae were 
of such a nature as to prove that the light emanated from 
heated matter in the condition of a gas, and that the prin- 


The Nineteenth and Twentieth Centuries 341 


cipal constituent of the gas was hydrogen. Only two of 
these wonderful bodies are visible to the naked eye, and 
those but faintly; but many thousands have been located 
with the telescope. When they began to be observed and 
studied by astronomers, it was supposed that all were 
merely star clusters. When Huggins announced that some 
of them were wholly gaseous, the fact was regarded as 
confirmatory of the famous nebular hypothesis of Laplace, 
as to the origin of the solar system. 

He was also the first to apply this method of investiga- 
tion to the light emanating from comets, and showed that 
at least a part of it was not reflected sunlight, but origi- 
nated in the nucleus of the comet itself. He was the first 
extensive employer of the Doppler principle, for the meas- 
urement of such stellar velocities as were ascertainable by 
that method. This field of study, calling as it did for very 
delicate and accurate observational work, and high mathe- 
matical ability in drawing conclusions from notes, led the 
way for the collection of data relating to the drift of the 
stars among themselves, which has added enormously to 
our knowledge of the nature and immensity of the Uni. 
verse, in which our earth is such a comparatively minute 
speck. 

He also made the earliest experiments in celestial pho- 
tography. This line of research at first produced very 
unsatisfactory results, in fact, no results at all; because, 
in the immature condition of the art at the time, when 
only wet plates were known, long time exposures were an 
impossibility. But when the dry gelatin plate was in- 
vented by Goodwin in 1898, exposures for hours became 
possible, thus permitting the collection of enough light to 
reveal objects so faint, as to be beyond the ability of the 
most powerful telescopes to report to the human eye. Thus, 
step by step, has the mind of man been able to reach out 
farther and farther into the infinity of space, in which he 
finds himself a conscious atom. 

In recognition of his great services to science, many hon- 
ors came to Huggins. He was president of the Royal 
Astronomical Society from 1876 to 1878, and became head 


342 Beacon Lights of Science 


of the British Association for the Advancement of Science 
in 1891. He was the recipient of the Royal, the Copley, 
and the Rumford medals. 


SCHULZE (1825-1894) 


BIOLOGY 


Max JOHANN SIGISMOND SCHULZE was born at Freiburg 
in Germany, received a thorough technical education, and in 
1859 became professor of anatomy at the University of 
Bonn, where he remained during the active balance of his 
life, and where he completed a number of important investi- 
gations on animal and vegetable life. Among his most 
notable writings on these subjects may be cited that on the 
Turbellarian Worms (1851), on the Foraminiferae of the 
Adriatie (1854), on the Embryology of the Lamprey (1860) 
and on the Electric Organs of Fishes (1867). His great 
accomplishment, however, was the establishment of the 
chemical and physical identity of protoplasm as found in 
the animal and vegetable world. This was set forth in a 
monograph published in 1863, which at once attracted the 
attention of biologists throughout the world, coming, as it 
did, nearly at the same time as the appearance of Darwin’s 
great work on the Origin of Species. 

The substance found in the minute cells, and which con- 
stitutes so far as at present known the ultimate material 
of all vegetable and animal life, was given the name of pro- 
toplasm by the German botanist Mohl, who was engaged 
at the time in investigating the nature of the chlorophyl 
grains in the leaves of plants. Before him, Conti, in 1772, 
and Treviranus in 1807, had detected the motion of these 
grains. Mohl showed that this motion was due to the move- 
ments of the substance in which they were contained as 
minute floating particles. Later, several observers (Sie- 
bold, Kolliker, Remak, etc.), discovered a similar appear- 
ing and continually moving substance in the cellular struc- 
ture of certain animal tissues, and gave it the same name. 
Still later, in 1835, the French zoologist Dujardin, de- 


The Nineteenth and Twentieth Centuries 343 


tected the same material in the bodies of certain members 
of the primitive animal order of protozoa, and gave the 
name of ‘‘sarcode’’ to it. The German botanist Cohn in 
1850 advanced the opinion that sarcode and protoplasm 
were identical, and this was demonstrated to be the fact 
by Schulze in 1861. 

In appearance protoplasm is a colorless liquid of about 
the consistency of thin syrup, through which are scattered 
highly refractive microscopic granules. It is regarded by 
biologists as the physical basis of all forms of living organ- 
isms, both animal and vegetable. It constantly exhibits 
motions of contraction, expansion, protrusion of parts, and 
other visible alterations of form by which translation from 
one place to another is effected. It reacts vigorously to 
touch, temperature and to chemical stimulus. Under 
analysis it yields mainly carbon, oxygen, hydrogen and 
nitrogen, and in smaller amounts phosphates and sulphates 
of potassium, calcium and magnesium, besides traces of 
sodium, iron and chlorine. Hertwig describes it as ‘‘not 
a chemical compound, but a morphological conception.”’ 
~ Which is the same as saying that its properties are not 
explainable by chemical analysis, but must be—and doubt- 
less will be in due time—by study of its activities as re- 
vealed by the microscope. 


BATES (1825-1892) 


NATURAL HISTORY 


Henry WALTER BATES was born at Leicester, England. 
His education was limited to the fundamentals, and at an 
early age he was apprenticed to a hosier, and later was 
a clerk in a commercial establishment at Burton-on- 
Trent. While there employed he became interested in the 
study of insect life, and devoted all his spare time and 
vacations to making collections, and reading such books as 
he could obtain on the subject. He finally met the natural- 
ist Wallace. They became firm friends, and by the sale 
of duplicate specimens accumulated sufficient means to 


344 Beacon Lights of Science 


undertake a trip to Brazil, landing at Para at the mouth 
of the Amazon river in 1848, with the intention of explor. 
ing its valley. To accomplish this with the least risk and 
to the greatest advantage, they divided the country between 
them, Wallace taking that to the north of the river, and 
Bates to the south. The latter spent three years with Para 
as headquarters, and seven in the upper tributaries of the 
great stream. 

The result of his work was an unusually fine collection, 
in which more than eight thousand specimens were entirely 
new to science. Included were five hundred of butterflies. 
These, in South America, attain remarkable size and ex- 
traordinary beauty. With this accumulation he returned 
to England in 1859, and in 1863 published ‘‘The Naturalist 
on the River Amazon,’’ which was at once recognized as 
the most valuable work of its kind up to that date, and 
remains today a classic. A later work, published in 1865, 
and entitled ‘‘Contributions to Insect Life of the Amazon 
Valley,’’ drew from Darwin very hearty congratulations. 
In it, in writing of the butterflies, he enlarged on the sub- 
ject of mimicry among these beautiful creatures, and ad- 
vaneed a theory in explanation which, though ingenious, 
is not considered satisfactory. The butterflies belong to the 
order Lepidoptera, which also includes the moths. Both 
are characterized by the possession of four wings. In the 
former all are capable of separate motion. In the latter 
the two on each side are connected and move together. 
Other distinctions are that the moths are nocturnal in 
habit, and hold their wings horizontally outstretched when 
at rest; while the butterflies are day-loving insects, and 
when in repose hold their wings vertically against each 
other. Both are beautifully marked and colored in wing 
and body, but these features in the butterflies are far more 
elaborate and showy. Together they contsitute a most in- 
teresting and important order, and play a large part in the 
fertilization of plants. In tropical regions they attain 
ereat size and develop wonderful colorings. Specimens of 
the tiger Swallow-tail butterfly have been found with a 
wing extension of twelve to fourteen inches. 


The Nineteenth and Twentieth Centuries 345 


Bates’s theory of mimicry was an effort to explain certain 
curious conditions which he found existing in connection 
with that species of the butterfly to which has been given 
the technical name of Helaconidae. These possess a very 
offensive odor, and an unpleasant taste, which renders them 
immune from the attack of insectivorous animals and birds. 
They seem to be aware of this, for, though brilliantly eol- 
ored and marked, they make no attempts at concealment. 
Another species, called the Pieridae, has not been provided 
by nature with the protective odor and taste, and is eagerly 
hunted by its enemies as a choice morsel. To offset this 
disadvantage it has developed (or is naturally gifted with) 
markings and colorings which so closely resemble those of 
the Heliconidae as to aid them materially in the struggle 
for existence. How this mimicry is effected—if it is of 
that nature—has not yet been explained. It has been found 
to exist as a fact in other species of those insects, in certain 
varieties of bees and wasps, and to some extent even among 
vertebrates. Both Fritz Muller and Wallace attacked the 
problem, but their explanations are regarded as no better 
than that of Bates. At the present time the subject is 
considered an open question by naturalists. 


HUXLEY (1825-1895) 


BIOLOGY 


THomas Henry Huxuey was born in a suburb of Lon- 
Gon of well-to-do parents, and received an excellent educa- 
tion in the sciences, graduating at the age of twenty from 
the Charing Cross medical school with the degree of A.B., 
and as a medalist at the University of London. In the fol- 
lowing year he was appointed assistant surgeon on the 
Rattlesnake of the Royal Navy, which was ordered to Aus- 
tralia to survey and study the great barrier reef on the 
eastern coast of that continent. The task lasted four years, 
during which he devoted the most of his time to the study 
of the marine life of that interesting region. His first 
monograph, on the Medusae (jelly fishes), published during 


346 Beacon Lights of Science 


his absence, placed him at once in the front rank of living 
biologists, by reason of his demonstration in it that the 
inner and outer membranes of these organisms corre- 
sponded exactly to the two primary germinal layers of the 
vertebrate embryo, a discovery which was the basis of a true 
conception of the affinity of animal life. 

On his return to England in 1851 he was elected a mem- 
ber of the Royal Society, and in the following year pre- 
sented with its medal. In 1854 he was appointed to the 
chair of natural history and paleontology at the Royal 
School of Mine’. Here his great ability, and unusual charm 
as a lecturer, at once attracted attention, and quickly 
brought him distinction and honor. In 1855 he was ten- 
dered the chair of comparative anatomy at the Royal In- 
stitution ; in 1863 the Hunterian professorship at the Royal 
College of Surgeons; in 1868 the presidency of the Ethno- 
logical Society; in 1869 that of the Geological Society, and 
in 1870 of the British Association for the Advancement of 
Science. He was elected rector of the University of Aber- 
deen in 1872, the professor of biology at the College of the 
Sciences in 1881, the president of the Royal Society in 
1883, and in 1892 a Privy Councilor of the Realm. 

Aside from his very important discovery already men 
tioned, his exceptional ability as an expositor, coupled with 
the clarity and incisiveness of the language he used in his 
lectures and writings, has never been surpassed among his 
countrymen. Perhaps the most remarkable example of 
these qualities was displayed in his lecture in 1858 on the 
‘‘Origin of the Vertebrate Skull.’’ But he is chiefly re- 
membered at the present day as among the first of those 
who accepted whole-heartedly the theory of evolution as 
cutlined in Darwin’s ‘‘Origin of Species.’? He undertook 
a veritable crusade in disseminating knowledge of its de- 
tails and implications, among the masses by lectures, and 
among the intelligentsia by his writings. His book, ‘‘Man’s 
Place in Nature,’’ is rightly regarded as his greatest lit- 
erary production. While he accepted tentatively Darwin’s 
view of the cause of evolution, that is, Natural Selection, 
and the Survival of the Fittest, as most probably the cor- 


The Nineteenth and Twentieth Centuries 347 


rect one, he held that clear and undoubted proof of it had 
not yet been produced, and urged that the question be 
regarded as open and unsettled until further evidences 
were discovered. On the other hand, he dissented abso- 
lutely from the explanation advocated by Lamarck, that 
of ‘‘use inheritance.’’ 

In certain quarters Huxley was regarded for a time with 
suspicion, because of his invention and application of the 
word ‘‘agnostic,’’ as an attitude of mind. By those he 
was ranked as an atheist, though his whole life as since 
studied reveals him to have been a man of strong religious 
tendencies. To him, knowledge must be a result of repeated 
experiences, and any mental conception which could not 
be so verified he thought should be placed in the category 
of unknown and perhaps unknowable things, belief in which 
eould not be expected of rational beings. But simultan- 
eously he insisted that the mind should always be held open 
for the reception of proofs through experiences, and should 
never be influenced by unsupported Authority. In this he 
represents correctly the mental attitude of the scientists of 
the present day. 


BUCKLAND (1826-1880) 
NATURAL HISTORY 


FRANCIS TREVELYAN BucKLAND was born at Oxford, 
England, his father at the time occupying the post of 
canon at the cathedral of Christ’s Church there. The lat- 
ter was a man of considerable literary ability, and, in an 
amateur way, a student of geology. The lad’s mother was 
a pearl among women, and the two were devoted to each 
other. 

Francis early developed a taste for natural history in 
its aspect of animal life. His disposition was gentle and 
genial. Pets took naturally to him. He had no difficulty in 
winning the confidence of any of the smaller animals, even of 
those that had not been domesticated. He was naturally given 


348 Beacon Lights of Science 


an excellent education, entered Oxford College at the age 
of eighteen, took his degree with honor, and in 1848 was 
enrolled as a medical student at St. George’s Hospital. 
While there he wrote an article on ‘‘Rats’’ which appeared 
in Bentley’s ‘‘Miscellany,’’ and inaugurated his career as 
an author. In 1854, having ereditably completed his term 
at the hospital, he was appointed assistant surgeon of the 
Life Guards. While occupying this position he contributed 
many articles on natural history to current periodicals, 
entered the lecture field, and gradually became recognized 
as an authority of note in his subject. 

In 1863 he resigned his position with the Guards, took 
up the study of fishes as a specialty, and traveled exten- 
sively on the continent collecting their eggs, investigating 
their habits, and taking notes of all devices encountered 
which had for their object their protection or improvement. 
One of his most interesting experiments was to freeze a 
quantity of fertilized trout eggs in ice, and ship the block 
to Australia in a refrigerator. The journey took more 
than three months in those days, but when what remained 
of the cake of ice was put into a weir properly provided 
with running water, and melted, the fish in a short time 
were hatched, and entered upon a healthy and vigorous 
life. In 1864 he turned his attention to oyster culture, and 
in 1867 attained the summit of his ambition by receiving 
the appointment from the government of National Inspec- 
tor of Fisheries, a position which he held for the balance 
of his too brief life, and in which it is not too much to 
say, he conferred enormous benefits on his country, by 
enlarging to a remarkable extent the consumption and 
supply of sea food. In addition, through contributed ar- 
ticles to the press, the technical and outdoor life periodi- 
eals, and by lectures, he spread the knowledge he acquired 
so entertainingly, and at the same time so truthfully and 
accurately, that at the time of his death he ranked easily 
as the chief world authority on sea food. To him the 
American Fisheries Commission owes much in the way of 
advice for the protection and rearing of food fishes. He 
took a prominent part in securing an international agree- 


The Nineteenth and Twentieth Centuries 349 


ment to prevent the extermination of the North Atlantic 
fur seal. He devised the best form of ladders to assist 
salmon in reaching their natural spawning grounds in 
rivers obstructed by falls or dams. He secured legislation 
for the protection of desirable sea birds. At the jubilee 
anniversary of the Society for the Prevention of Cruelty 
to Animals in 1874, he was perhaps the most prominent 
speaker, and easily the one who drew the largest audiences. 
His account of the life history of the crabs and lobsters is 
absorbingly interesting. 

His premature death was the result of lung trouble, 
brought about by excessive work and exposure while prose- 
euting his investigations of marine life. With men of his 
temperament the search for knowledge becomes an obses- 
sion, which will not permit of rest, so long as a question 
that the mind has propounded remains unanswered, or 
death terminates the quest. Perhaps it merely forces a 
rest until, again refreshed, the loved work can be resumed 
in another phase of existence. 


BERTHELOT (1827-1907) 


CHEMISTRY 


PrerRE EuaitNnr MArRcELLIN BERTHELOT was a native son 
of Paris, and educated at the College of Henry IV in that 
city, graduating with high honors in 1854, upon which oe- 
easion he delivered a remarkable thesis on the synthesis of 
animal fats, the analysis of which had been effected in 1823 
by Chevreul. In this essay he showed that glycerin was 
an alcohol, thus introducing for the first time the idea 
of polyatomic alcohols. 

In 1851 he took the chair of organic chemistry at the 
Paris School of Pharmacy, and in 1865 the professorship 
in that branch of science at the Collége de France, which 
he held during the remainder of his active career. In 1873 
he was elected a member of the French Institute, and in 
1889 became permanent secretary of the Academy of Sci- 
ences. 


350 Beacon Lights of Science 


Berthelot is regarded as the pioneer in the very modern 
science of organic chemistry, and one of the most brilliant 
of experimenters. ‘The science of thermo-chemistry also 
owes much to his studies. In this department of investiga- 
tion he announced what he called the third law of thermo- 
dynamics, namely, ‘‘that the heat evolved during a chemi- 
cal reaction measures the power of the reaction.’’ This 
principle, however, has since been found to be only partially 
true, or rather, true in many eases, but not in all, and 
hence is not at present considered in the category of dem- 
onstrated natural laws, as the term is understood. 

Organic chemistry is that department of general chem- 
istry which has to do with all those forms of matter— 
found exclusively in the animal and vegetable world— 
which are products of the phenomenon ealled life; as dis- 
tinguished from inorganic chemistry whose domain is con- 
fined to the mineral kingdom, including water and the 
atmosphere. As late as 1825 it was believed, even among 
men of science, that a force existed entirely different in 
kind from all the forces then known, which was the cause 
back of all kinds of life, and as impossible to understand 
and manipulate as life itself. It was called the ‘‘vital 
foree.’’ In certain circles it was even deemed impious to 
investigate its operations, or to endeavor to modify its 
consequences. All such ideas have long since passed away. 
Today, while our horticulturists cannot make a loganberry 
in the laboratory, they can induce a blackberry bush to 
produce one, and all sorts of similar feats have been accom- 
plished in the manipulation of animal life, as stock breeders 
well know. But it is mainly in the modern manufacturing 
arts, such as the production of dyes, drugs, perfumes and 
fibers, without the aid of life processes formerly relied upon, 
that the organic chemist of the present day has scored his 
ereatest triumphs. 

Comparatively few of the eighty-eight known elements 
of which all matter is composed are found in living organ- 
isms; if we exclude the skeletal parts such as bones, shells 
and the silicious integuments of trees, bushes and plants, 
ninety-five per cent of all animal and vegetable tissue is 


The Nineteenth and Twentieth Centuries 351 


composed of the elements carbon, hydrogen, oxygen and 
nitrogen, with sodium, potassium, phosphorus, sulphur and 
chlorine constituting the most of the other five per cent. 
With the first four mentioned, and with the compounds of 
carbon preeminently, the science of organic chemistry has 
mainly to do. The first, so well known in its familiar form 
of charcoal and coal, is found in nature in two other forms, 
viz., graphite and the diamond. Associated with the coals 
are usually many impurities, yet the soot which, to some 
extent always, is produced during their combustion, is the 
pure element. Graphite, the material of which pencils are 
made, is also carbon in its native condition, and is always 
more or less contaminated with earthy impurities, but can 
generally be separated from them by mechanical means. 
Strangely enough, carbon, when in this allotropie form, is 
so incombustible as to be available and highly desirable in 
the manufacture of crucibles, in which metals of high in- 
fusibility can be melted. The diamond is the crystallized 
form of the element. In all organic compounds earbon is 
an invariable constituent, and generally much the largest. 


LISTER (1827-1912) 


MEDICINE 


JOSEPH ListER lived at Upton, England, and received 
his early education at a school conducted by the Society of 
Friends (Quakers). From there he went to the University 
of London, where he took his degree in medicine at the 
age of twenty-seven. Specializing in surgery, he soon at- 
tained a high reputation, which was recognized by being 
appointed surgeon to the Queen. His eminence and sue- 
cess was due, not only to his manual skill, and knowledge of 
anatomy, but to his insistence on scrupulous cleanliness, 
and the large use of disinfectants in his hospital wards. 
He knew from extended experience the advantages of such 
a régime and perhaps had some idea of the reasons be- 
hind his methods, but he was not enough of a chemist to 


352 Beacon Lights of Scrence 


earry on the laboratory work necessary to explain them 
scientifically. 

When, however, Pasteur gave to the world his great 
work on putrefaction and fermentation, he at once realized 
that the danger in wounds, and in all surgical operations, 
lay in infection from bacteria, and the other micro-organ- 
isms always present in the purest air, and under the most 
cleanly conditions possible, and that some method must 
be developed to combat this danger. 

He at once set about the preparation of antiseptic liquids 
and disinfectants, and in devising methods of surgical prac- 
tice which would exclude germs of all kinds from the 
vicinity of the patient under operation, or would cleanse 
a wound already infected. One of his first preparations 
was the well-known ‘‘listerine,’’ a solution of borie and 
benzoie acid with thymol. He devised a method of con- 
ducting certain operations under an atomie spray of car- 
bolic acid, and adopted many scheme for keeping instru- 
ments sterilized, for keeping his hands, and those of his 
assistants, free from germs, and the air in the operating 
room as pure as possible. Some of his early methods have 
since fallen into disuse, or, have been improved by the 
employment of chemicals better adapted to the ends sought, 
but the recognition of the importance of the exclusion of 
living germs from wounds, of the danger of their intro- 
duction from the air, on the instruments employed, 
and by the hands of those operating, and of the value of 
sermicidal drugs, has been a permanent acquisition of 
enormous value to the surgical art. 

In 1880, both Cambridge and Oxford conferred the de- 
gree of LL.D. on Lister, and he received the gold medal 
of the Royal Society. He was made a baronent in 1883, 
and a peer of the realm in 1897. The noun ‘‘listerine’’ and 
the verb ‘‘to listerize’’ have both been incorporated into 
the English language, and constitute a permanent memorial 
to his honor. 


The Nineteenth and Twentieth Centuries 353 


KEKULE (1829-1896) 


CHEMISTRY 


FreiprRicH August KEKULE VON SHADOWITZ was born at 
Darmstadt in Germany, and after passing through the 
course at Heidelberg became at first a tutor there, and in 
1858 professor of chemistry at the University of Ghent. In 
1865 he was transferred to the same post at the University 
of Bonn, and remained there for the balance of his career 
as an instructor, engaged, while not in the lecture room, in 
researches in the field of organic chemistry. 

As the element carbon is present in all organic com- 
pounds to a greater extent than any other, it was quite 
natural that Kekulé’s first discovery of importance should 
have been its quadrivalent property. By valence, in this 
connection, is meant the relative capacity of an element to 
combine with other elements. Valence is a conception 
which has sprung from the atomic and molecular theories 
of matter. The majority of the elements appear to have 
but one valency and hence are called univalent. Thus 
hydrogen can hold only one atom of any element with 
which it is capable of entering into a stable compound hav- 
ing properties entirely different from that of the atoms of 
which it is composed. Oxygen and sulphur, as well as the 
group known as the alkaline earths—sodium, potassium 
and lithium—are divalent. Aluminum and zine are each 
trivalent. Many of the others have more than one valency. 
Carbon was shown by Kekulé to be quadrivalent, which 
means that its atom can combine chemically with four 
atoms of any univalent element, or with two of divalent 
ones, with which it can combine at all; for all of the ele- 
ments refuse to combine in any way with some of the 
others. On the foundation of this discovery has been raised 
the modern ‘‘structural theory’’ of chemical compounds in 
a way the usefulness of which can hardly be overestimated. 
- On the other hand, valency as a general theory for all 
the elements is not yet thoroughly enough demonstrated 
or developed to be perfectly satisfactory in all cases. In 


354 Beacon Lights of Scrence 


fact, it is only so in the ease of carbon and a few others, 
and even with carbon, in the case of the gas carbon mon- 
oxide (CO) it seems to act divalently, unless it be assumed 
in this instance that the oxygen (normally divalent) is here 
acting quadrivalently. Other exceptions might be cited. 
So that while Kekulé’s discovery has been very fruitful, the 
subject is much in need of further and more profound re- 
search, 


MARSH (1831-1899) 


NATURAL HISTORY 


OTHNIEL CHARLES MArsH was a native of Lockport, New 
York, and after his graduation at Yale studied in Germany. 
When he returned from that country he was offered the 
chair of paleontology at Yale and the curatorship of its 
geological museum, and continued an honored member of 
its faculty for the remainder of his active life. In 1877 the 
Geological Society of London, of which he was a member, 
awarded him the first Bigsby medal. In the following year 
he was elected president of the American Association for 
the Advancement of Science, and served in the same eapac- 
ity for the National Academy of Science from 1883 until 
1895. He also was the recipient of the Cuvier prize from 
the French Academy of Sciences for his researches and dis- 
eoveries in the field of zoology. 

His outstanding achievements, however, were in the do- 
main of paleontology, the science of fossilized and ancient 
or pre-historic animal life, and consisted largely in the ex- 
ploration of localities in the Great Plains region of the 
United States, where he discovered and recovered from 
their graves in the rocks and unconsolidated sediments, the 
remains of over four hundred new species of vertebrates, 
among them being such interesting types as huge tapirs, 
flying lizards and toothed birds. His greatest discovery 
was the fossilized bones of the ancestors of the horse family. 

Until Marsh’s labors became known it was generally held 
that this beautiful and useful animal had been evolved in 


The Nineteenth and Twentieth Centuries 355 


western Asia, and that vast upland area may yet prove 
to have been the real place of his origin; but up to date all 
indications are to the effect that it was on the North Ameri- 
can continent, though he appears to have become extinct 
there many ages ago, and was unknown to the aborigines 
of both of the American continents when first introduced 
by the Spanish conquerors in the early years of the 16th 
century. 

It is now held that the horse arose as a branch from the 
older family of the tapirs, one of the members of the order 
of Pachydermata, which includes the elephant, rhinoceros, 
hippopotamus and hog. The first known member of his 
stem was the Hyracotherium, an animal about the size of 
a rabbit. It is better known at present as the Eohippus. 
It had four toes on its front feet and three on its hind. Its 
bones were found in one of the early rocks (Wasatch) of 
the Eocene division of tertiary time which, according to 
present estimates places its age perhaps as much as ten 
million years in the past. 

A complete skeleton of his successor, the Protohippus, 
found in Wyoming, is in the American Museum of Natural 
History in New York. It is about the size of a half-grown 
fox. It had four toes in front and three behind, but the 
two side toes of the last only just touched the ground. 
Following him, and in the Oligocene (White River) rocks 
of the middle Tertiary, the Mesohippus was found, of about 
the size of a sheep, with three toes in front but only one 
of them firmly touching the ground, and the same number 
similarly conditioned in the rear. In this animal the long 
skull of the modern horse began to appear as a marked 
feature. The first specimen was found by Marsh in 1875. 

Next came the Protohippus, which had attained the size 
of a Great Dane dog or a small Shetland pony. He trav- 
eled on one toe (the middle) on all four feet, but still 
carried on each, two side toes well off the ground, and 
merely useless rudiments. His teeth now begin to show 
the shape and character of those peculiar to the horse, the 
crown longer, the ridges higher and more complicated, and 
strongly enameled, and between the last the dentine or 


356 Beacon Inghts of Science 


cement begins to show, which, being softer, wears away 
faster than the enamel, and so makes the grinding teeth 
such effective tools for disposing of the hard silicious grains 
and grasses which had by then become his principal food. 

In the upper rocks of the Tertiary and the lower ones of 
the Quaternary, that is, about the time when man began 
to appear, was found his successor, the Pliohippus, a little 
taller than his predecessor, his face a little longer, his side 
toes now mere rudiment, and his teeth approaching closely 
the shape and character of those of the existing animal. 

The horse first appeared in historic time among the 
Assyrians, whose home was in the uplands of Armenia and 
Persia around the northern boundaries of the Mesopo- 
tamian valley. By that time—four to five thousand years 
ago—they had become domesticated, and it is considered 
that their ancestors were tamed and trained for the service 
of man by the semi-Mongolian people who, several mil- 
lenniums previously, dwelt in that region to the east and 
northeast of the Caspian sea which is now called Turkestan, 
and was formerly known as Tartary. 

The horse family has three other living members, the 
zebra, the ass and the donkey. The first has been found 
only in Africa, and is distinctly a dweller in mountain 
and forested areas, where it has acquired its peculiar coat 
as a protection against its natural enemy, the lion. The 
African wild ass often attains the height of fourteen hands 
(four feet, eight inches) or more, and is also distinctively 
a lover of hilly and well-timbered regions. His Asiatic 
relative, however, is smaller, and prefers semi-arid and 
treeless plains. The donkey is believed to be the domesti- 
cated variety of the African ass, which has lost size and 
spirit through centuries and probably millenniums of inter- 
breeding, hard usage and abuse. But in recent years the 
species has been vastly improved in the United States in 
employing it for the breeding of mules. 


The Nineteenth and Twentieth Centuries 357 


MAXWELL (1831-1879) 


PHYSICS 


JAMES CLERK-MAXWELL was born at Edinburgh, Scot- 
land, and secured his primary education at the academy 
of that city. At an early age he developed unusual mathe- 
matical abilities, which were zealously cultivated along 
with physics, chemistry, philosophy and laboratory work, 
as he passed through the university. From there, at the 
age of nineteen, he was sent to Cambridge, where he grad- 
uated in 1854 with high honors. Two years later he took 
the chair of natural philosophy at Marischal College, Aber- 
deen, and in 1860 the same position at King’s College, Lon- 
don. From there in 1871 he went to Cambridge, to take 
the professorship in experimental physics, and the direc- 
torship of the Cavendish Laboratory, which was completed 
under his supervision, and placed at his command. He 
retained this position during the balance of his short life, 
passing away with the reputation of being the leading 
physicist and mathematician of his day, and one of the 
ereatest of all time. 

He published a number of scientific monographs, but the 
one that is regarded by long odds as his greatest, appeared 
in 1873, under the title of ‘‘ Electricity and Magnetism.’’ 
In this paper he developed his electro-magnetic theory of 
light, demonstrating mathematically the ultimate identity 
of the three phenomena, and showing that each was a 
manifestation in a different way of the energy existing in 
space. His conclusions were later confirmed experimentally 
by Hertz, who not only produced elctro-magnetic waves or 
undulations, but showed that they were propagated just 
as those of light are, experiencing reflection, refraction and 
polarization, and also moving at the same velocity. 

Maxwell’s calculations and investigations assume the 
existence of the universal ether of space, as a transporting 
medium. The actuality of this substance (like that of the 
force of gravitation) has never been scientifically demon- 
strated, and the theory of relativity recently advanced by 


358 Beacon Lights of Science 


Einstein implies that neither (the ether or gravitation) are 
necessary hypotheses for a correct explanation of the phe- 
nomena of the universe. Einstein’s conclusions have so 
far been experimentally confirmed, and it is the expectation 
of many scientists that they will continue to be. If, in the 
end, it becomes clear that the ether, or the force of gravi- 
tation, or both are unnecessary for a proper understanding 
of nature as it appears to the senses, it is not expected that 
the conclusions of Maxwell or Newton will be affected. On 
the other hand the scientists of today are looking for new 
light on both of these subjects, and are awaiting their com- 
ing with confidence and composure. 

The conception of ‘‘action at a distance, without any con- 
necting medium’’ is one that is at present incomprehensible 
to the human mind. But we have much good evidence to 
the effect that the mental capacity of man is greater now 
than it has been, from which it is a fair conclusion that 
it is capable of acquiring still further powers of under- 
standing. 


TYLOR (1832-1917) 


BIOLOGY 


EpWARD BuRNETT TYLOR was a native of London, re- 
eeived his education in fundamentals in that city, and be- 
gan his active business life as an operative in his father’s 
brass foundry. But having a delicate constitution he was 
eompelled to abandon the work, and was provided with 
the means for travel. In 1855 he came to the United 
States, and in the following year passed on to Mexico, 
where he became interested in the study of the ancient 
civilization of the Aztecs and Mayas, the remains of which 
are so abundant in the great Valley of Mexico, in the states 
of Campeche and Chiapas, and in the republic of Guate- 
mala to the south of them. Finding in these the oppor- 
tunity for congenial research and study he devoted the 
balance of his life to their investigation, and in 1859 began 
the publication of his discoveries in a volume entitled ‘‘ Ana- 


The Nineteenth and Twentieth Centuries 359 


huae.’’ This was followed in 1865 by his ‘‘ Researches in 
the Early History of Mankind,’’ in 1871 by ‘‘ Primitive 
Culture,’’ in 1881 by ‘‘Anthropology,’’ and in 1900 by 
‘““The Natural History of Religion.’’ In these books he 
opened a completely new field for investigation, and being 
a careful and keen observer as well as possessing a pleasant 
style, his writings have not only been widely read but 
have given such an impetus to the study of human antiqui- 
ties in all parts of the world that he is regarded as the 
founder of the science of anthropology, as well as the 
supreme authority up to the present time on the prehis- 
toric civilizations of Mexico and Central America. In 
1896, in recognition of the value of his work in this direc- 
tion, he was elected to the chair of the science at Oxford, 
and continued in that honorable position for the remainder 
of his active career. 

Anthropology, the science of Man, should not be con- 
founded with Archaeology, the science of the remains of 
the doings and acts of ancient man. While the former has 
to do more or less with those abstract physical phenomena 
like gravity, energy, affinity, vitality (in the vegetable 
world) and motility in that of animals (including man), it 
adds as its own particular subject that of mentality, and 
regards the latter as its exclusive field of research. 

As man is a member of the animal world, a knowledge 
of zoology and comparative anatomy is at the foundation 
of anthropological science. To understand correctly the 
possible physical activities of the human body a thorough 
acquaintance with the nervous and muscular system is re- 
quired, and to comprehend mentality the reactions of which 
the brain is capable must be known. Thus physiology and 
psychology are necessary tools of the anthropologist. On 
the other hand, as the subject enlarged under investigation, 
specialization began, so that today sociology, the science of 
human groupings; ethnology, the science of human races; 
philology, the science of human speech, and mythology, the 
science of religions, and others, have come into existence 
as sub-divisions of the main field of research. 

In time and place anthropology has fundamentally to 


360 Beacon LInghts of Science 


do with that specific era in the history of all the human 
races that have emerged from savagery and barbarism into 
more or less of civilization; when the man, by reason of 
his mental capacity, began to make and use tools, to form 
theories of nature and life, to provide somewhat for the 
necessities of tomorrow as a result of the experiences of 
yesterday, to scheme for something more than food and 
shelter, and to exhibit the germs of an appreciation of 
beauty and sentiment by the development of the arts of 
music, architecture, painting and sculpture. Above all, to 
devise means for recording his actions and thoughts in 
pictographs and in systems of script. When this stage of 
development is attained, history for him has begun, and 
the science of anthropology properly merges itself into that 
of archaeology. 


CROOKES (1832-1919) 


PHYSICS 


WILLIAM CROOKES was born in London, and completed 
his education at the Royal College of Chemistry in that 
eity. In 1854 he became connected with the Radcliffe Ob- 
servatory at Oxford, and in the following year, the pro- 
fessor of chemistry at the Chester Training College. In 
1859 he founded the Chemical News, and continued to be 
its editor during the remainder of his life. 

He was a brilliant investigator in many departments of 
theoretical and applied chemistry, and the discoverer of 
several important principles. He was an authority on 
sanitation and the disposal of sewage. He devised the 
method of attaining a high vacuum, which made the in- 
candescent light bulb a possibility. He discovered the rare 
metal thallium, and investigated its interesting properties. 
He was an important contributor to the science of spec- 
troscopy, and of radiation, for the display of which he 
devised the radiometer, which has since been made so 
delicate as to be capable of registering the energy carried 
by ethereal undulations. He was not the inventor of the 


The Nineteenth and Twentieth Centuries 361 


well-known apparatus for the study of rarefied gases which 
bears his name (Crookes’ tubes), that idea having origi- 
nated with Hithoff, a German chemist; but he took a large 
part in improving its construction, and employed it very 
extensively in his investigations of the phenomenon of 
fluorescence, the explanation of which was made by Stokes. 

In 1879 he advanced for consideration by the scientific 
world his theory of a fourth, or ultra-gaseous state of mat- 
ter. 

He received many honors during his lifetime, among 
them being the Nobel prize of 1917 for chemistry, and the 
Order of Merit in 1910. 

The metal thallium when pure is of a silvery white color, 
and so soft that it can be scratched with a piece of pure 
lead. It can be squeezed, but not drawn into the form of 
a wire, but has little tenacity or elasticity. It is slightly 
heavier than lead, melts at a lower temperature and tar- 
nishes quickly in the air. Its compounds are extremely 
poisonous. In the Periodic System of the elements it is 
next to the bottom of the vertical group headed by boron, 
and which contains in the order given aluminum, scandium, 
gallium, yttrium, indium, lanthanum and erbium, and 
stands between mercury and lead in the eleventh of the 
horizontal series. So far little use has been found for it. 
During recent years, as a result of the discovery of radium 
and the series of disintegration products from it and the 
metal thorium, it has been thought by investigators of those 
phenomena that it may prove to be the final disintegration 
step of thorium, as lead has proved to be of radium. 

When the flame produced by the combustion of thallium 
is examined in the spectroscope, a brilliant green line ap- 
pears at one place, which is so characteristic that the pres- 
ence of the metal in very minute quantities can be detected 
by the test. It occurs in nature in very few minerals, and 
almost always in combination with the non-metal selenium. 


362 Beacon Lights of Scvence 


NOBEL (1833-1896) 


HIGH EXPLOSIVES 


ALFRED BERNARD NoBEL was a native of Stockholm, 
Sweden. He acquired his education in St. Petersburg, to 
which city his father’s business took him during his youth. 
In 1850 he came to the United States, and studied under 
the distinguished engineer, John Ericsson, for several years. 
It was during this period of his life that he became im- 
pressed with the great need in the engineering arts of an 
explosive of quicker action, and greater convenience in 
handling and usage, than the gunpowder that up to then 
was the only agent available. 

The modern discovery of gunpowder is generally attrib- 
uted to Roger Bacon, who wrote of it in 1270 as ‘‘a sub- 
stance that, if confined and ignited, would explode with 
the noise of thunder, and tear to pieces the vessel in which 
it was stored.’’ But there are manuscripts in existence 
which seem to indicate beyond question that an explosive 
compound of sulphur, saltpeter and charcoal, was known 
to the Arabs before that date. The Chinese are also be- 
lieved to have been more or less acquainted with the sub- 
stance centuries previously, and to have used it effectively 
in the siege of Lo-Yang and Pian-King in 1232. It is well 
attested that it was employed in cannon at the battle of 
Crécy in 1345. For 500 years thereafter, this compara- 
tively mild article answered all the requirements for such 
a substance, being mainly demanded for destructive pur- 
pose in war. 

In 1845 or 1846, a German chemist named Schonbein, 
discovered by accident the dangerously explosive qualities 
of the compound now ealled gun-cotton, and in the year 
following, the Italian chemist Sobrero, in the same fortui- 
tous way, made the acquaintance of nitro-glycerin. Neither 
of these men pushed their investigations any farther,’ 
though Sobrera seems to have committed to writing the 
opinion that ‘‘if a way could be found to handle and use 
the article safely, it might be employed advantageously in 


The Nineteenth and Twentieth Centuries 363 
rock blasting.’’ Meantime, he prepared a very dilute aleo- 
holie solution of it, for use in the medical art, where it still 
is employed for the relief of certain obstructions in the 
circulatory system, where it appears to have the power of 
dilating the arteries and capillaries, and so relieving the 
strain on the heart. 

Nobel’s attention: seems to have been drawn to these 
discoveries, for in 1863 he took out a patent for the manu- 
facture of a compound, consisting of a mixture of nitro- 
glycerin and gunpowder. The former, being a liquid, and 
having the habit of exploding on the slightest occasion 
under the influence of a small shock, was exceedingly dan- 
gerous to handle. But when mixed with gunpowder it 
became a pasty solid, which was less dangerous, and was 
also capable of being molded and used in the form of a 
cartridge. However, gunpowder is in no sense an ab- 
serbent, and cartridges made of such a mixture had the 
unpleasant habit of sweating, and also leaking, at a little 
above the ordinary temperature, in which condition they 
were fully as dangerous as the liquid nitroglycerin. So 
many fatal accidents occurred when the article was used, 
that it was quickly abandoned. However, in 1867, he sub- 
stituted a mineral product called kieselguhr, for the gun- 
powder, using about 25 per cent by weight of it, to 75 per 
cent of nitroglycerin, and gave the name of dynamite to 
the mixture. As kieselguhr consists of the minute and 
empty shells of infusorians, it possessed the absorbitive and 
retentive power required to produce a safe compound. 
Later wood pulp was substituted. The latter being itself 
capable of combustion, added to the power of the article, 
and at the same time proved entirely satisfactory as an 
absorbent. 

In 1876 Nobel brought out his blasting gelatine, which, 
for certain purposes, is an improvement on dynamite. Pur- 
suing the investigation farther, he took out a large number 
of patents for explosive compounds (129 altogether), es- 
tablished factories in all parts of the world where such 
an article is in demand for mining, quarrying, etc., and 
accumulated a large fortune, the major part of which, at 


364 Beacon Lights of Science 


his death, passed to the Nobel Prize Fund of $8,400,000, 
from the interest of which the trustees annually award 
five prizes of $40,000 each, to the most deserving persons 
in as many departments of human activity, namely, physics, 
chemistry, physiology or medicine, literary work of an 
idealistic nature, and in the interests of universal peace. 

The world has benefited enormously by the discovery of 
safe ways of utilizing the power of high explosives. The 
arts of mining and of under water excavation have been 
completely revolutionized since their advent. And while, 
unfortunately, these substances—of which hundreds are 
now known—are also used to a considerable extent in the 
destructive art of war, yet their very terrible powers can- 
not fail ultimately to bring to an end the barbarous scourge 
of battle. 


LUBBOCK (1834-1907) 


NATURAL HISTORY 


JOHN Lussock (Lord Avebury) was the son of a London 
banker, himself an astronomer and mathematician of note. 
The young man was educated at Eton and Oxford, entered 
public life in 1858, and 1890 succeeded Lord Rosebery as 
president of the London County Council where, as a man 
of affairs and a wise legislator, he served his constituents 
to their great satisfaction. 

Early in his career he became interested in the sciences 
of archaeology and entomology, and having the leisure 
and the means to indulge his inclinations, did much to 
advance the status of both. His ‘‘ Prehistoric Times,’’ pub- 
lished in 1865, was the first notable effort to collect and ar- 
range all the information of reliability that had accumu- 
lated to that date on the subject of ancient human remains 
and artifacts, and for twenty years or more was a standard 
text book in its line. It was followed in 1870 by his ‘‘Ori- 
gins of Civilizations,’’ of equal value as an inspiration for 
others to follow. 

In entomology he was the discoverer of the extraordinary 


The Nineteenth and Twentieth Centuries 365 


fact that the common insect known as the May fly moults 
twenty-three times during the course of its larval life of 
from one to three years, while the fly itself lives but a few 
days after attaining its final term of existence. In 1867 
he published a monograph on the life history of that very 
remarkable minute creature known as the pauropus which, 
though not over one-twentieth of an inch in length, and 
gifted at birth with only three pairs of legs, develops dur- 
ing its life nine additional pairs. This was followed in 1873 
by the publication of his chief systematic work on the Col- 
lembola and the Thysanura, the lowest order of six-footed 
insects, and the ones which seem to represent the first struc- 
tural advance on their ancestors, the worms. Although 
this work, as well as several others on similar subjects, is 
now considered somewhat out of date, it was an authority 
for many years, and did much to encourage study and re- 
search in the then obscure and little known field of an 
important department of organic life. Discoveries of this 
nature may seem trivial and scarcely worth recording, yet 
it has been shown by innumerable instances that knowledge 
gained of the minute and apparently insignificant in na- 
ture invariably leads in due time to revelations well worth 
while, and often of supreme importance to science as a 
whole. Much of Lubbock’s work in entomology was of 
this inspirational kind. He was a man of wide learning 
for his time, and of broad sympathies and high intelligence, 


WEHISMANN (1834-1914) 


ZOOLOGY 


Aucust WEISSMAN was a native of Frankfort-on-the- 
Main in Germany, took his degree in medicine at the Uni- 
versity of Gottingen, served for a time as clinical assis- 
tant at Rostock, and then for three years traveled and 
served in the hospitals of Vienna, Bologna and Paris. In 
1863 he took a special course in geology at the University 
of Giessen, and in 1871 became a full professor of that 
science in the University of Freiburg. 


366 Beacon Lights of Science 


When Darwin published his ‘‘Origin of Species,’’ Weis- 
mann was among the first of German scientists to became 
an enthusiastic supporter of the views there advocated. 
In fact, he went somewhat beyond Darwin. The latter ad- 
vanced natural selection as the main cause of variability, 
but believed that there were other contributing agencies 
which should not be ignored. Weismann insisted that it 
alone, as embodied in the phrase ‘‘the survival of the fit- 
test’’ was the one and all sufficient cause of mutability. 
The controversy over these divergences was animated and 
is not yet ended. But while it was most actively in prog- 
ress it had the effect of completely demolishing the old 
theory to the effect that each species arose as a separate and 
distinct act of creation. On the other hand, the debate 
brought to the surface the theory of ‘‘use-inheritance,’’ 
which originated with Lamarck. According to this, char- 
acter or form acquired during the lifetime of an individual 
could be, and often was transmitted to descendants. Weis- 
mann scouted this in toto, and considered that he had 
disproved it by docking the tails of white mice through 
nineteen generations without producing a tailess individual 
at the end of the experiment. However, it is held by mod- 
ern evolutionists that characteristics of several kinds 
formed by adaptation to changes in environment, in cli- 
mate, or by any species of external stimulus, may be, and 
often are transmitted. Many obvious examples of this kind 
ean be cited. The pointer breed of dog, without training, 
holds his tail rigidly level and on a line with his nose, 
when he has located his prey by scent. In the whale, whose 
ancestors were land animals, and who still brings forth its 
young alive and nurses them, the legs have become fins. 

Weismann’s investigations in other lines were notable. 
His study of the embryology of the fly, which appeared in 
1864, is considered very remarkable. He was the first to 
discover the real nature of the changes that occur in the 
metamorphosis of insects, by locating the germ of the final 
and perfect form (the imaginal bud) in the body of the 
larva. This led to the complete abandonment of the theory 
of preformation which originated with Malpighi (1628- 


The Nineteenth and Twentieth Centuries 367 


1694), and according to which—for instance—all the parts 
and organs of the chick were present in the egg. Weis- 
mann was a most enthusiastic microscopist, and pursued 
the extremely minute in organisms so persistently as to 
injure his eyesight beyond repair. Compelled then to con- 
tinue his studies without the aid of observation, he became 
more speculative in conclusions, and in his later years ex- 
pressed some opinions that have not been sustained. On 
the other hand, being a bold and keen theorist, most of 
them have been amply confirmed. Perhaps the most not- 
able instance of the latter is the case of the phenomenon of 
heredity, which he was the first to announce as having a 
physical basis, as now universally held. 


LANGLEY (1834-1906) 


AVIATION 


SAMUEL Pirrpont LANGLEY was born at Roxbury, Massa- 
chusetts, was educated in the Boston Latin School, and 
after some years of study and travel in Hurope, became 
professor of mathematics at the United States Naval Acad- 
emy at Annapolis, Md. In 1867 he took the chair of 
astronomy at the Western University of Pennsylvania, and 
in 1886 was elected president of the American Association 
for the Advancement of Science. In the following year he 
was appointed secretary of the Smithsonian Institution at 
Washington. In 1894 he was awarded the degree of D.C.L. 
by Oxford University, and became a member of the Royal 
Society of London, from whom he received the Rumford 
medal. He was also given the Janssen medal by the Insti- 
tute of France. 

Langley was an accomplished mathematician, and an 
observational astronomer of high reputation. He was the 
inventor of the bolometer, a wonderfully delicate instru- 
ment for the detection of minute changes in temperature, 
and particularly for such as are due to the absorption of 
radiant heat. With this instrument he made solar observa- 
tions on Pike’s Peak in Colorado (1878), on Mt. Etna in 


368 Beacon Lights of Science 


Sicily (1878-1879) and on Mt. Whitney in California 
(1881), which added greatly to the stock of knowledge of 
solar energy. In this particular line of research his con- 
clusions may be concisely stated as follows: Starting 
from the mathematical premise that the earth receives 
1/2,300,000,000th part of the total solar radiation, he de- 
duced the figure 3 as the most probable value of the solar 
constant, which is defined as ‘‘the amount of heat required 
to raise one gram of water three degrees centigrade per 
minute, for each normally exposed square centimeter of 
its surface.’’ The present accepted figure is 3.127. 

Langley is universally accorded the great honor of hav- 
ing been the founder of the science of aviation. During 
the latter part of his career he became deeply interested 
in this subject, greatly to the regret of many of his friends 
and associates, who regarded his activities in that direction 
as indications of the gradual failure of a brilliant mind. 
He was, however, a man with the courage of his convic- 
tions, and by 1897 had become so thoroughly convinced 
that mechanical flight was possible, that he built a machine 
on the principles he had worked out, which was wrecked in 
the attempt to put it into operation. It remained for the 
Wright brothers not many years later to demonstrate the 
accuracy of his predictions. 


MENDELEEF (1834-1907) 


CHEMISTRY 


Dimitri IVANOVITCH MENDELEEF was a native of Tobolsk, 
Siberia. He studied in the local primary schools, and at 
the age of sixteen was sent to the Institute of Pedagogy at 
St. Petersburg, where he specialized in the natural sciences, 
his inclinations being strongly towards physics and chem- 
istry. Upon his graduation in 1856 he was appointed a 
tutor in the university, and in 1863 took the chair of chem- 
istry at the St. Petersburg Institute of Technology, and 
two years later the same post in the university. In 1876, 
under government authority, he made a technical study of 
the petroleum industries in the United States, and at the 


The Nineteenth and Twentieth Centuries 369 


Russian oil fields at the foot of the Caucasus mountains. 
In 1893 he became a government official in the Department 
of Finance, and remained there during the balance of his 
active life. 

His claim for distinction as a noted discoverer in the 
domain of science, was firmly established upon the publi- 
cation in 1868 of his ‘‘Klements of Chemistry,’’ in which 
he set forth with remarkable clarity and ability what is 
now known as the Periodic Law of the Elements. This 
law, as stated by him, was as follows: 

‘‘The properties of the elements, as well as the forms 
and properties of their compounds, are in periodic de- 
pendence on, or constitute a periodic function of, their 
atomic weights.’’ 

In his day only 64 elements were known. At the pres- 
ent time they number 88. Of those that have been added 
to the list since the publication of his law, three—gallium, 
germanium, and scandium—were predicted by him, their 
place in his table, and their chemical properties accurately 
given, and the association (mineralogically) in which they 
should be found correctly indicated. All three were dis- 
covered during his lifetime. Those since discovered have 
all found a place in his table, but it became necessary to 
enlarge this, when the inert elementary gases were discov- 
ered by Ramsay in 1894, and to alter its arrangement some- 
what, though without affecting the principle of periodicity 
which is at the foundation of the law. In fact these changes 
rather strengthen the system. 

In extension of his general law as quoted, he announced 
upon its publication the following conclusions or deduc- 
tions: 

1. The elements which have the lowest atomic weights, 
are those most widely distributed in nature, and also repre- 
sent the most typical characteristics found in the successive © 
series of the table. 

2. The atomic weight determines the character of the 
element. 

3. From a consideration of their position in the system, 
new analogies can be discovered between elements. 


370 Beacon Lights of Science 


4. It may be expected that new elements will be dis- 
covered to fill blank spaces within the table, and their 
properties ean be predicted, from a consideration of those 
of the adjoining elements. 

5. Errors in the assumed atomic weights may be detected 
through an irregularity in the position of an element in the 
System. 

All of these conclusions have, in a broad way, been veri- 
fied, though the anomalous positions of tellurium and 
iodine are still unexplained. 

Although at the present time the so-called elements are 
known to be composites, and no longer are regarded as 
elementary, yet Mendeleef’s law has lost none of its inter- 
est or value to the chemist, for it still correctly represents 
the fundamental units of matter upon which he operates, 
and probably always will. If, as seems now to be quite 
certain, the physicist succeeds in resolving these units into 
pure manifestations of energy, our conceptions of matter 
will undoubtedly require readjustment, but the methods 
of dealing with it in the laboratory are not likely to be 
altered. 


HAECKEL (1834-1919) 


EVOLUTION 


ERNEST HEINRICH HAECKEL was brought up at Potsdam 
in Germany, and completed his education at the Universi- 
ties of Berlin and Jena, specializing in medicine and physi- 
ology. After practicing the profession for a year, and 
finding the work uncongenial, he decided to devote himself 
to the natural sciences, and particularly to zoology. With 
that end in view he studied marine life at the island of 
Heligoland, at Naples, and at Messina. As a result of 
the publication of his investigations at these places, he 
was appointed to the chair of zoology at the University of 
Jena, and while occupying that position he was able to 
make numerous journeys to other places where observa- 
tions of oceanic life could be conducted advantageously, as 


The Nineteenth and Twentieth Centuries 371 


the Canary islands, the Norwegian coast, the Red and 
Adriatic seas, Ceylon, and the East Indies. Each of these 
furnished the material for the publication of a monograph 
of great value to science, as he was a close and accurate 
observer, and a clear reasoner. 

When Darwin’s ‘‘Origin of Species’’ appeared, Haeckel 
became an enthusiastic and generous advocate of evolution, 
and did more than any other continental writer of the time 
to disseminate its principles among the intelligent classes 
of central Europe. He is now remembered mainly on ac- 
count of his celebrated biogenetic law, the germ of which 
had already been hinted at by Baer, Agassiz and Fritz 
Miller. It may be concisely stated as follows: 

‘Every individual organism, in its development from 
the ovum, goes through a series of evolutionary stages, in 
each of which it represents a stage of the evolution of the 
class to which it belongs; and every such organism breeds 
true in so far as it is influenced by heredity, and becomes 
modified in so far as it is influenced by the conditions of 
its environment.’’ 

Haeckel also advanced for consideration what is called the 
‘*Gastraea Theorie,’’ according to which the gastrula stage 
in the development of animal life is to be regarded as a re- 
capitulation of a hypothetical common ancestor—the Gas- 
traea—the primitive animal form possessed of an intestinal 
organ or system, technically known as a gastrula. 


NEWCOMB (1835-1909) 


MATHEMATICS 


Simon NeEwcoms was a native of Nova Scotia, and re- 
ceived his primary education at a school conducted by his 
father. At the age of eighteen he came to the United 
States, became a citizen, and shortly obtained a position as 
teacher in a Maryland school. While there he became ac- 
quainted with some government officials who, recognizing 
his exceptional aptitude in mathematics, secured his ap- 
pointment in 1857 to the position of computer on the staff 


372 Beacon Lnghts of Science 


of the Nautical Almanac, the headquarters of which at the 
time was at Cambridge in Massachusetts. Taking advan- 
tage of the proximity of the Lawrence Scientific School he 
enrolled himself there, and was able to graduate in the 
following year with such distinction as to bring him in 
1861 the appointment to the chair of mathematics at the 
U.S. Naval Academy, where he superintended the installa- 
tion of the new 26-inch telescope at its Observatory. He 
was later a member of two government expeditions sent out 
to observe the transits of Venus in 1874 and 1882, one of 
which took him to the Cape of Good Hope. In 1877 he 
was appointed director of the Nautical Almanac. publica- 
tion, and continued in charge of its preparation and issue 
until retired for age in 1897. 

The Nautical Almanac, issued annually by the American 
government is, like similar publications by the British, 
French and German governments, a volume furnishing data 
required by navigators to enable them at any time to find 
their position at sea, and to know the state of the tides 
at all their ports of call. In addition, it supplies a great 
variety of general information as to currents, latest known 
positions of derelicts, changes in coast lights and signals, 
and other such matter. In the line of astronomical affairs 
it gives the position of the moon for every hour of the year, 
the latitude and longitude of the sun for every day, the 
place in the heavens of the most important of the stars, and 
full details of eclipses, occultations, transits, ete. It is 
generally issued two or three years in advance, for the 
sake of mariners contemplating long voyages. 

It will not be difficult to understand that a publication 
of this kind calls not only for a thorough knowledge of 
nautical astronomy, and high mathematical ability, but also 
extreme accuracy in the details of editing. For over thirty 
years Newcomb conducted this very important department 
with success. During his ineumbency he was also able 
to appreciably increase the world’s stock of knowledge as 
to the peculiarities in the movements of the moon. Being 
the nearest celestial body to the earth, it is the most im- 
portant factor in the phenomenon of the tides; while at the 


The Nineteenth and Twentieth Centuries 373 


same time it is perturbed in so many ways during its 
monthly journey, by the combined gravitative powers of 
the earth and the sun, as to make a closely approximate 
statement of its position at any time a matter of most 
intricate computation. Elsewhere in this volume the de- 
tails of the ‘‘Lunar Theory’’ and the ‘‘Problem of the 
Three Bodies in Space’’ will be found. 

Newcomb’s standing as a mathematician was amply rec- 
ognized during his lifetime. He was elected to membership 
in nearly all the scientific societies in the world, and was 
the first American since Franklin to be made an officer of 
the French Legion of Honor. He was the recipient of the 
Copley, Huygens, Royal Society and Bruce medals, and 
served terms as president of five of the American scien- 
tific associations. 


LOCKYER (1836-1920) 


ASTRONOMY 


JOSEPH NoRMAN LOCKYER was born at Rugby, England. 
He was given a general classical education at schools in 
his own country and on the continent of Europe; and while 
serving from 1857 to 1870 as an employee in the War 
Office, devoted his leisure hours to studies and investiga- 
tions in astronomy. In the years 1870 and 1871 he was 
a member of Lord Devonshire’s Commission on scientific 
instruction, and in 1875 was connected with the science 
and art department of the Kensington Museum; serving 
at the same time on the government eclipse expeditions. 
When the Royal College in London was established he was 
appointed its professor of physical astronomy, and made 
director of its observatory. From that time until he re- 
tired from active life he was one of the prominent figures 
among British scientists. 

The discovery with which his name is most frequently 
associated is that of the elementary gas helium, in 1868. It 
was made on the sun, instead of on the earth, and by the 
use of that wonderful tool of modern science, the spectro- 


374 Beacon Lights of Scrence 


scope. While studying the solar spectrum he detected a 
bright yellow line which did not correspond to those of 
any known element. The discovery was quite analogous 
to that of the element coronium which the same instrument 
reveals as existent in the solar corona, and which has not 
yet been found on the earth. But in 1895, nearly thirty 
years after Lockyer announced the existence of helium, 
Ramsay, while examining the rare mineral clevite, identi- 
fied its content in helium. It has since been found in all 
ores of uranium, in many mineral waters, in some mete- 
orites, in the atmosphere; and lately as a component of the 
output of several gas wells in Texas in sufficient quantity 
to make its recovery commercially practicable. 

In his studies of the spots on the sun he reached another 
eonclusion not so spectacular, but perhaps more impor- 
tant. This was to the effect that there exists a relation 
between the number and area covered by them, and the 
weather on the earth. They appear like holes or vast de- 
pressions in the photosphere. In the middle of each is a 
black spot, surrounded by a spiral or radial formation of 
a brighter appearance. In size their diameter ranges from 
500 to 60,000 miles. They begin as mere dots, and after 
enlarging to a maximum, slowly decline in size and disap- 
pear. The majority occur in the vicinity of the sun’s 
equator, and none have been observed at a greater distance 
from it than 45° N. or 8. It is thought by astronomers 
that they represent eruptions of some kind from the inner- 
most nucleus of the sun, into and through the intensely 
heated gaseous and luminous layer surrounding it called 
the photosphere. It had been known for a long time that 
the total area occupied by these spots varied periodically. 
During about a term of eleven years the surface spotted 
attains a maximum and a minimum condition. Lockyer 
perceived that at these extremes the precipitation of rain 
and snow on the earth was also at a maximum and mini- 
mum, and continued observation since has demonstrated 
that the connection between the two phenomena was real; 
but why, has not yet been ascertained. Nor has any satis- 
tactory theory of the cause of the spots been advanced. 


The Nineteenth and Twentieth Centuries 375 


A third notable discovery of Lockyer’s—made simulta- 
neously also by the French astronomer Janssen—was a 
method of studying the solar corona without waiting for 
an eclipse. This has been developed to a high degree, and 
has been of great assistance in enlarging our stock of 
knowledge of the luminary. 

Lockyer wrote and published numerous valuable astro- 
nomical monographs. He was awarded the Rumford medal 
by the Royal Society in 1874 and was subsequently knighted 
by the King in recognition of his services to the cause of 
science. 


HILL (1838-1914) 


ASTRONOMY 


GroRGE WILLIAM Hii was born in New York City, and 
received his education at Rutgers College in that city. In 
1861 he became attached to the staff of the Nautical Al- 
manac, and was elected a member of the National Academy 
of Sciences in 1872 in consequence of the excellent work 
done in that connection. He was a writer of note on celes- 
tial mechanics and mathematics, his most important work 
in these lines being ‘‘A New Theory of Jupiter and 
Saturn,’’ published in 1890. In 1874 he was awarded the 
gold medal of the Royal Astronomical Society of England 
for his ‘‘conspicuously fine work on the mechanics of the 
Moon.’’ 

Although the nearest body to the earth in space, the pe- 
euliarities of the motions of the moon are not yet com- 
pletely understood by astronomers. This is due to the fact 
that its movements are, to all intents and purposes, gov- 
erned almost entirely by the sun and the earth. For 
though the other planets of the solar system also do act 
on it, their distance is so great, and their mass—relative 
to those of the sun and the earth—so small, that the effects 
are negligible. 

But the mathematical problem of the ‘‘Three Bodies 
in Space,’’ which is presented in this case, is one that has 


376 Beacon Lights of Science 


not yet been solved; and by some mathematicians is re- 
garded as insoluble, though both Laplace and Clairault 
devised equations which produced approximately close re- 
sults as checked up with observation. The difficulties in 
the way will be made clear through a statement of the 
fundamental conditions existing, using round numbers 
only. The mass of the sun is 330,000 times that of the 
earth, and its distance is 389 times that which separates 
the earth from the moon. Applying the laws of gravita- 
tion as stated by Newton to these figures, it will be found 
that the attraction exerted by the sun on the moon is 2.18 
times that exerted on it by the earth. Hence, if the earth 
were fixed in space, the sun would inevitably pull the moon 
away from it. But the sun attracts both simultaneously, 
with the result that both fall towards it together. Com- 
bining that effect with the inertia (centrifugal force) of 
the two, the final result is the path in which the earth 
travels in its annual journey around the sun, carrying the 
moon with it. 

At new moon and at full moon, when the moon, the earth 
and the sun are disposed along approximately a straight 
line with respect to each other, the attraction of the latter 
in the first case tends to pull the moon more than normally 
away from the earth, and in the second to assist it in 
holding it. At first quarter, when the moon is racing away 
from the sun, the pull of the latter on the satellite is at 
aminimum. At the third quarter, when the moon is racing 
towards that luminary, it is at a maximum. In the period 
of a lunar month, the net effect of these contending forces 
is, that during each lunar revolution, the attractive power 
of the earth is overbalanced by that of the sun, to the 
extent of about 1/360th, in consequence of which the lunar 
month is each time lengthened by about one hour. 

A second cause of disturbance is due to the shape of the 
moon’s orbit which, like those of all the planets and satel- 
lites, is an ellipse, and not a circle as thought by Copernicus. 
Therefore, at one place in its monthly trip it is at a maxi- 
mum distance (apogee) from the earth, and at another, 
directly opposite, at a minimum distance (perigee). At 


The Nineteenth and Twentieth Centuries 377 


the latter the pull of the earth is naturally greater than at 
the former. This produces an oscillation in the position 
of these two points (apsides), with the result that in a 
term of about nine years they make a complete revolution 
in the path of its orbit. 

Five other causes of disturbance exist, all too complicated 
in their nature to be explained in the space that can be 
given here to the subject. One is called the ‘‘variation.’’ 
Another the ‘‘regression of the nodes.’’ <A third the ‘‘evic- 
tion.’? The fourth is the ‘‘annual equation,’’ and the 
fifth is the ‘‘secular variation.’’ It is no wonder, there- 
fore, that under such a complication of conditions the 
mathematicians have been unable so far to produce a com- 
plete solution of the problem of the movements. With all 
the planets of the solar system that have satellites these 
same perturbations exist to a greater or less extent, and 
the difficulties they cause to their astronomers may, with- 
out compunction, be left to them to solve. But with us, as 
the moon is the principal agent in producing the tides, the 
matter cannot be neglected by those whose business it is 
to predict (in the Nautical Almanac) the periods of high 
and low water at the principal ocean ports of the world. 
Hill’s investigation of the subject led to conclusions which, 
while not perfect, were so much closer than those of La- 
place and Clairault, as to bring him the recognition men- 
tioned from the English Royal Society. 


PERKIN (1838-1907) 


CHEMISTRY 


Wiuw1AM H. Perkin was of English birth, the son of 
parents in comfortable circumstances, his father being a 
contractor and builder of standing, whose ambition it was 
to make an architect of his boy. With this end in view 
he was afforded as good an education in the fundamentals 
as could be procured, and was apparently quite willing to 
follow along the lines that had been chosen for him. But 
at the age of fourteen he chanced to witness at the home 


378 Beacon Lights of Science 


of a schoolmate some experiments in chemistry, and became 
so fascinated that he decided then and there to take up 
that science as a profession. At the time he was a student 
at the College of the City of London. Chemistry just then 
did not rank very highly as an art, nor present many 
opportunities for the earning of a living. But the teacher 
of it at the College happened to be an enthusiast. Noting 
the deep interest that Perkin took in his lectures he made 
him his assistant, and later advised him to attend those 
of Faraday at the Royal College, who was then at the 
summit of his career. After listening once to the course 
he attended it a second time, and by earnest pleadings 
induced his father to abandon the intention of making him 
an architect, and to back him for a full course at the Royal 
institution. In two years he had become so proficient in 
the art that he was made an assistant to the chief profes- 
sor. At home he set up a laboratory in an unused room 
where he could work evenings and during the vacations. 
There, in the Easter holidays of 1856 he made his first 
great discovery. 

His chief at the College had suggested to him as a vaca- 
tion study, an attempt to produce synthetically from coal 
tar the drug quinine, which was then in great demand at 
a very high price. He did not succeed in accomplishing 
this; but in its place, and more by accident than design, he 
made the first of the analine colors, that lovely and highly 
prized reddish-purple dye now known as ‘‘mauve,’’ but 
which at first went by the name of Perkin’s Purple. Work- 
ing on this for many days he at last ascertained its compo- 
sition, and learned just how to make it from the raw mate- 
rial available. As soon as he had produced sufficient for 
a practical test, he submitted it for trial to one of the large 
establishments in England engaged in the dyeing business. 
They reported favorably on it, and in the strongest terms. 

His next step was to procure his patent, and after that, 
the means to begin its manufacture. Here he encountered 
innumerable difficulties. Capital was not eager to back a 
new and unproved industry. But his father and an elder 
brother had by this time become so fully convinced of the 


The Nineteenth and Twentieth Centuries 379 


importance of his discovery, that they joined him with all 
their available resources, and under the firm name of 
Perkin & Sons began the erection in 1857 of a building on 
a suitable site at the village of Greenford Green, near Har- 
row. Here young Perkin designed and installed the ma- 
chinery of the plant, and after securing a supply of the raw 
material required from the gas works at Glasgow, and the 
nitric and sulphurie acids and hydrogen to extract the 
analine from the coal tar, was able to begin the production 
of the former in quantity, and from it to extract the coveted 
dye. 

When first used with cotton goods it was found neces- 
sary to discover a new mordant, to render it ‘‘fast.’’ 
Among those tried out tannin was found the most satis- 
factory, and Perkin was the first to employ it for that pur- 
pose. He also introduced the practice of using a soap 
bath in the treatment of silk fabrics. In the early stages 
of the enterprise dyers were chary of adopting this new 
laboratory product as a substitute for the vegetable and 
animal dyes that from ancient times had been their re- 
liance, but their hesitation was finally overcome. The busi- 
ness became a great financial success, particularly after 
Perkin in his laboratory, and then in his factory, began 
the production of other colors. In a short time factories 
using the Perkin patents sprang up in various parts of 
Great Britain and on the continent, and the young chem- 
ist became recognized as the leading authority on dyes. In 
1861, when only twenty-three years old, he was invited by 
the Chemical Society of London to deliver a lecture on his 
specialty. In the audience he had the unusual satisfaction 
of seeing his former preceptor, the distinguished chemist 
Faraday who, at its termination, warmly congratulated 
him on his work. 

In 1866 Perkin was elected a fellow of the Royal Society. 
In 1874 he sold his plants and his patents, and retired 
from active business to enjoy the delights of a life of 
chemical research, and with ample means to satisfy the 
inclination. In 1879, in recognition of important new dis- 
coveries, he was awarded the medal of the Royal Society, 


4 


380 Beacon Lights of Science 


and ten years later the Davy medal. In 1906 he was 
knighted. That year, being the fiftieth anniversary of his 
discovery of mauve, he was honored in various ways by 
chemical societies in all parts of the world. In America 
he was presented with the first impress of the Perkin medal, 
founded in his honor, and since awarded annually for dis- 
tinguished service in the field of applied chemistry. 
Unfortunately, on account of the indifference of the Brit- 
ish government, and of the great English universities, to 
progress in applied science, which was ranked as a trade, 
and consequently somewhat beneath the dignity of gentle- 
men, the command of the dyestuff industry passed away 
from that country after the death of its founder, and was 
transferred to the control of Germany, where it expanded so 
enormously that, at the opening of the Great War the 
world was dependent on that country not only for its dyes, 
but for a long list of synthetic products the manufacture 
of which had sprung from the original impulse of Perkin’s 
discovery and labor. Perhaps since then the valuable les- 
son has been learned, that it is more honorable to be a 
worker, than to be an idler living on the labor of others. - 


ABBE (1838-1916) 


METEOROLOGY 


CLEVELAND ABBE was a native of New York, and gradu- 
ated in 1857 at the College of that city. Desiring to 
specialize in astronomy, he pursued that science for two 
years at the University of Michigan, and for the following 
four at Cambridge University in England. From there he 
went to the Pulkowa Observatory in Russia, where he 
served as assistant observer for two years, when he was 
offered the position of director of the observatory at Cin- 
cinnati, Ohio. There he began a system of daily weather 
forecasts, based upon simultaneous observations reported by 
wire from various points to the east and west of that city. 
For nearly five years he continued making these predictions 
until, by increased experience and the enlargement of facil- 


ose 26nd bmov 7 saouas fo KwapvIp jouo1vN OC) 








ZION ISH 


ir 


— 


os ‘ _ 
fit 4. 
dF 
URIVER 4 





The Nineteenth and Twentieth Centuries 381 


ities, the percentage of accuracy reached a figure that at- 
tracted the attention of the Federal government, and led 
to an invitation to remove to Washington and take charge 
of the Weather Bureau. Under his capable management 
this department at once became of great value to agricul- 
turists and mariners. Its methods and principles have since 
spread into nearly all parts of the civilized world. Its 
forecasts in the United States for heavy storms, cold waves, 
injurious frosts and hot spells are now verified almost with- 
out exception, but those for rain not so successfully. In 
addition to the central station at Washington, and seven 
major sub-stations at Boston, Chicago, Galveston, Denver, 
Los Angeles, San Francisco and Portland, Ore., there are 
over fifty minor stations, including those at the Philippines, 
Guam, Hawaii, Cuba, Porto Rico and the Canal Zone, be- 
sides several in Alaska. As atmospheric disturbances and 
variations have been found to advance from the west to 
the east, and from the polar regions toward the equatorial 
regions, the position of the United States is such as to make 
it—with Canada—the natural starting point for observa- 
tions of weather phenomena for practically the balance of 
the northern hemisphere of the globe. 

In 1879 Dr. Abbe introduced the existing system of 
standard time and hourly meridians, which is universal 
over the North American continent. He published several 
interesting works, the best known of which is probably 
‘<The Mechanics of the EHarth’s Atmosphere,’’ which ap- 
peared in 1891, has been translated into most of the Euro- 
pean languages, and ranks as a classic on its subject. He 
received the degree of LL.D. in 1887 from the University 
of Michigan, and the same in 1896 from that of Glasgow. 
He has been a lecturer of note on the science of meteor- 


ology. 


GIBBS (1839-1903) 


MATHEMATICS 


JOSIAH WILLARD GIBBS was born at New Haven, Con- 
necticut, and graduated at Yale college in 1858. He then 


382 Beacon Lights of Science 


went to Europe, studying in turn at the universities of 
Paris, Berlin and Heidelberg. Returning to the United 
States in 1871, he was tendered the chair of mathematical 
physics at Yale, and remained there for the balance of 
his life. During that period of thirty-two years he pub- 
lished two notable works on his specialty. The first, which 
appeared in 1875, was entitled ‘‘Equlibrium of Hetero- 
geneous Substances.’’ The second was ‘‘An Elementary 
Treatise on Statistical Mechanics’’ and came from the press 
in 1880. In 1881 he began his studies on Vector Analysis, 
applying their conclusions to problems in crystallography, 
in light phenomena, and in the computation of the orbits 
of the planets and comets. These studies and investiga- 
tions rank very high in the literature of mathematical 
physics, and have been drawn on extensively by scientific 
investigators throughout the world. 

In mechanics, a vector is a member of a machine which 
conveys the power delivered at one point of it to the place 
where work is to be performed by its means. The most 
familiar examples are the connecting rods of a locomotive 
and the walking beam of a paddle-wheel steamboat. In 
mathematics the word is used to express a quantity such 
as has the properties of a straight line of a definite length, 
and extending in a definite direction. Or, differently de- 
scribed, a quantity which, being added to any point of 
space, gives as the sum another point which is at a certain 
distance and in a certain direction from the first one. In 
this the analogy with the connecting rod of the locomotive 
is more clearly brought out. Illustrations of this mathe- 
matical conception are linear displacements, linear mo- 
mentum, linear acceleration, linear velocity and force act- 
ing on a particle. Remembering that a mathematical point 
has position but no magnitude, and that a straight line has 
direction but no thickness, it can be understood that a 
vector may be likened to one or an assemblage of points 
moving in a certain direction and for a certain distance. 

It is of course out of the question in a work of this kind 
to go into a subject so technical in any detail. Nor would 
it be possible without using liberally the language of mathe- 


The Nineteenth and Twentieth Centuries 383 


matics, that is, the diagrams of geometry and trigonometry, 
and the symbols of algebra and the calculus. But the 
average reader will have no difficulty in understanding 
that the properties of vectors are of importance in the con- 
struction and operation of complicated machinery, and of 
great value in comprehending the structure and unraveling 
the movements of that inconceivably vast mechanism the 
Universe, where suns and stars are to us but points, and 
whose motions—together with those of the planets and satel- 
lites they carry along in their train, may be investigated by 
vectors whose lengths and directions are constantly varying 
to the extent of a point at a time. 


COPE (1840-1897) 


NATURAL HISTORY 


EDWARD DRINKER COPE was a native of the city of Phila- 
delphia. Huis primary education was received in private 
schools, following which he took a course in anatomy at 
the University of Pennsylvania. After devoting nearly 
thirty years to exploratory work in the fossiliferous regions 
of the western parts of the United States under Wheeler 
and Hayden, and to research in zoology and comparative 
anatomy, he was appointed professor of geology and paleon- 
tology of the University of Pennsylvania upon the resigna- 
tion of Leidy. From 1878 until his death he was the editor 
of the American Naturalist. 

As a collector and describer of fossils he ranked, at the 
elose of the last century, at the head of international 
paleontologists. Though his work in that line did not re- 
sult in discoveries so spectacular as those of Marsh and 
Leidy, yet the immensity of his collection was impressive, 
for it contained parts of almost all extinct animal forms 
discovered on the North American continent up to the time 
when he abandoned field work. 

Of quite equal importance were his studies in the field 
of reptilian life. This was at the time a department of 
natural history where work was long overdue. ‘The first 
attempt at a systematic arrangement of these creatures was 


384 Beacon Lights of Science 


made by the English naturalist Ray, in 1693. The classi- 
fication principle which he adopted was correct, but his 
field of observation was too limited to permit of success. 
The system employed by Linnaeus was faulty, and had to 
be abandoned. Cope was able to add to a thorough knowledge 
of living forms, an unexampled collection of the remains 
of extinct ones; and as this order of animal life is very 
ancient—the first fossils being of early Permian age—at- 
tained its prime in Jurassic and Cretaceous time, and has 
since (comparatively speaking) almost disappeared, he was 
really the first of the naturalists to be in a position to 
arrange its membership properly. 

As the order arose from the amphibians, and from it one 
branch evolved into the birds, and the other into the mam- 
mals, its importance as a connecting link between the re- 
mote past and the present can readily be understood. No 
department of the animal kingdom flourished to anything 
like its extent, or produced individuals as large, or species 
as diverse, grotesque and even horrible. At one period 
they dominated in the sea, on the land and in the air, 
and to such an extent that other orders were at times 
threatened with extinction, for their range at their prime 
was almost cosmopolitan. 

The outstanding characteristics of reptiles are as follows: 
They are lung breathers, but the organs are not subdivided 
as with birds and mammals, nor are they provided with 
the means for the continuous introduction and expulsion 
of air which exists in the forms that have succeeded them. 
The skin, having no covering in the way of feathers or 
hair, is a poor preserver of bodily heat. Hence the blood 
has a temperature but little above the water or air in 
which they live, and they are known as cold-blooded crea- 
tures, like the fishes. They have no external ears, yet their 
sense of hearing is good. They are all egg layers, and with 
but few exceptions these are not incubated by the mother, 
but left to be hatched by the natural warmth of the sand 
or the decaying vegetation in which they are deposited. 
The skin of the egg contains little lime, is more like parch- 
ment than sbel!, and is always white. 


The Nineteenth and Twentieth Centuries 385 


Of the still living types, the snakes are the only ones that 
seem to be prospering. The heavily armored turtles and 
erocodiles are able to survive by having returned to the 
amphibian condition, and the land tortoises and lizards 
by becoming small, so that concealment from enemies is 
easier. 

Cope espoused the cause of evolution eagerly, but held 
that the cause of the origin of species had been accounted 
for more satisfactorily by Lamarck than by Darwin. 


KOVALEVSKY (1840-1891) 


EMBRYOLOGY 


ALEXANDER KOVALEVSKY spent his early years at Duna- 
berg, Russia. Having received a thorough education in 
fundamentals and the natural sciences, his tastes led him to 
specialize at first in zoology, and later in embryology, in 
which latter he became one of the eminent investigators 
and students of his day. 

He was the first to demonstrate the relationship of the 
ascidians (popularly called the sea-squirts) to the amphi- 
oxidae (lances, or sand lances), and the close alliance of 
both with the vertebrates. He discovered the gill slits in 
that strange worm-like marine invertebrate called belano- 
elossus, thereby fixing its place in nature as in the line of 
vertebrate ancestry. In the embryology and post embry- 
ological development of insects, his work was fundamental, 
and he made important contributions to the knowledge of 
the development and structure of various annelids 
(worms), and coelenterates (sea-anemones, corals, sponges, 
ete.) 

The science of embryology deals with the beginnings of 
individual life in the animal and vegetable worlds. In all 
eases the processes are fundamentally the result of similar 
causes, and may be of three kinds, namely, self-division, 
conjugation and sexual reproduction. The first is the 
primary or primitive method, and is the general system in 
that lowest division of animal life called the Protozoa, and 


386 Beacon Lights of Science 


also with the one-celled plants. The organism, after reach- 
ing maturity, simply divides into two organisms, each of 
which after maturing repeats the process. Or a budding 
process occurs, which is the method with all the higher 
plants. These two are known as the ‘‘fission’’ systems. 

Conjugation may be considered as an anticipation of the 
sexual method, but differs from it radically in that the 
conjugating bodies are each an entire plant or animal, and 
both disappear in the act. It is the process in certain of the 
uni-cellular plants, and with the infusoria. Thus, for ex- 
ample, a free swimming individual of the Heterometa (an 
infusorian which is found abundantly in infusions of ani- 
mal and vegetable matter in both fresh and salt water) 
approaches an anchored individual of its kind, the posterior 
ends coming into contact. They then coalesce, like two 
globules of water or mercury, into one mass. This moves 
around freely for a time, then rests, loses its external or- 
gans of locomotion, becomes coated with a comparatively 
tough skin, and finally bursts, pouring out a swarm of 
spores, each of which, like an egg or a seed, is capable of 
developing directly into a new individual. 

In the sexual system, in both the male and female indi- 
vidual a cell, apparently identical at the start with all the 
other cells, appears to be told off for reproduction, and 
after passage through certain organs becomes fitted for 
that duty. In the female that cell becomes the ovum or egg, 
and in the male the spermatozoon. After fertilization each 
such egg (or its analogue in plants, the seed, develops grad- 
ually into a new individual. It will be observed that in 
the lower forms of animal life and very generally in plants, 
quantity production is the main desideratum, and quality 
of secondary importance; while in the higher forms the 
contrary is the case. 


RAYLEIGH (1842-1919) 


PHYSICS 


JOHN WituiAM Strutt (Lord Rayleigh) was born in 
England, and completed his education at Cambridge in 


The Nineteenth and Twentieth Centuries 387 


1865 with high mathematical honors. From 1879 to 1884 
he oceupied the chair of experimental physics there, and 
in 1887 assumed the professorship of natural philosophy at 
the Royal Institute in London. In 1896 he became techni- 
eal adviser to the British Lighthouse Board, and continued 
in its service until his death. 

Although the chemist Cavendish nearly a century before 
had detected a small difference in density between the gas 
nitrogen when prepared chemically, and when obtained 
from purified air by the removal of its oxygen, he was not 
able to explain the reason, and the matter had been forgot- 
ten. Rayleigh, apparently without any knowledge of this, 
but because there was considerable uncertainty at the time 
as to the density of nitrogen, undertook in 1885, in asso- 
ciation with Ramsay, a redetermination of the properties 
of the gas. In the course of the investigation the inert 
element argon was discovered by them. Somewhat later, 
Ramsay, following up the lead so given, discovered four 
other inert gases, thus bringing to light for the first time 
a whole family or group of elements theretofore unknown, 
and to which a sixth has since been added. These are helion 
(formerly and still popularly called helium), neon, argon, 
krypton, xenon and niton, the last better known as yet as 
radium emanation. All exist normally in the atmosphere, 
argon to the extent of nearly one per cent, and the others 
in very much less quantity. 

Nitrogen itself is not a very active element, that is, it 
will unite directly with but few of the others, and such 
compounds as it will form are generally unstable. But the 
six above mentioned refuse chemical action absolutely. For 
this reason, after the surprise caused by their discovery 
had subsided, not much attention was paid to them, be- 
cause it did not seem that they could be put to any practi- 
eal use. Since then, however, their very inertness has been 
recognized as a valuable property. MHelion, fairly abun- 
dant, and the lightest, is the ideal gas for balloons and air 
ships. It possesses nearly the lifting power of hydrogen, 
and is non-inflammable. Argon, the most abundant of the 
six, and neon, much less so, have been found to be advan- 


388 Beacon Lights of Scrence 


tageous in illumination, and promise to be extensively em- 
ployed as soon as they can be obtained in sufficient quan- 
tity and at moderate cost. 

Rayleigh’s investigations and discoveries in other de- 
partments of science were notable and fruitful, especially 
in the phenomena of acoustics and optics, and in connec- 
tion with electrical standards. He was not a brilliant in- 
vestigator, but a most painstaking and thorough one. 

He became a fellow of the Royal Society in 1873, and 
was a member or corresponding member of several foreign 
scientific associations. In 1895 he received the Barnard 
medal of Columbia University for ‘‘conspicuous service to 
science.’’ 


DEWAR (1842-1923) 


PHYSICS 


JAMES Dewar was born at Kinecardine-on-Forth in Scot- 
land and received his education at the University of Edin- 
burgh where he became, after graduation, assistant profes- 
sor of chemistry. Later he received the appointment to 
the chair of experimental philosophy at Cambridge, and 
of chemistry at the Royal Institution at London. In 1897 
he was elected president of the British Chemical Society, 
and in 1902 of the British Association for the Advancement 
of Science. 

His first notable research was in the department of optics, 
where he advanced views on the physiological effects of 
light of different colors which, for a time, attracted great 
attention, in the belief that many diseases could be cured 
(or at least benefited) by submitting the body daily to the 
action of sunlight passed through glass transparent only 
to certain rays. Members of the older generation among 
my readers will remember what was then called rather 
derisively the ‘‘blue glass eraze.’’ But after extended 
trial so little of benefit resulted that the idea was aban- 
doned and quickly forgotten. 

Subsequently he turned to the subject of low tempera- 


The Nineteenth and Twentieth Centuries 389 


tures, in which he achieved a notable success in the lique- 
faction and solidification of the common gases. 

The lowest temperature obtainable by the mixture of salt 
and ice is — 22° Centigrade. But as early as 1824 
Bussy, by the rapid evaporation of sulphurous acid gas 
(SO,), secured a temperature of —65° C. Using this 
method he liquefied in turn chlorine, ammonia and cyano- 
gen, and solidified the last. Ten years later Thilorier, by 
first compressing carbon dioxide and cooling it, and then 
allowing it to expand suddenly, succeeded in solidifying a 
portion of it. Faraday, by 1845, had liquefied all the gases 
then known except hydrogen, oxygen, nitrogen, nitric oxide 
and marsh gas, by combining high pressure with low tem- 
peratures, and expressed the opinion that these could be 
liquefied if certain temperatures and pressures could be 
realized which then were impossible. After his death the 
werk was continued by Andrews, who reached the conclu- 
sion in 1869 that for each of the gases there was a certain 
temperature which must be produced, before any amount 
of compression would result in liquefaction. This he called 
its ‘‘eritical temperature,’’ and determined the figure for 
earbon dioxide at 31° C. This discovery, which has since 
been amply verified, explained the failure of Faraday, as 
mentioned, and led the way to the invention of what is 
known as the regenerative method, which was first put into 
operation by Houston in 1874, in the production of liquid 
air. By it, a portion of a gas under severe pressure is 
allowed to expand to a certain extent. In the act the tem- 
perature of the expanding part falls markedly. In that 
condition it is then caused to circulate around the vessel 
containing the remainder of the gas, whose temperature is 
thus materially reduced. This process is then repeated 
again and again until the critical temperature is reached, 
whereupon liquefaction ensues. 

Using this method Dewar produced liquid oxygen, nitro- 
gen and air in quantity, and by 1893 had solidified the last. 
By 1898 he was able to obtain a considerable amount of 
liquid hydrogen, and a couple of years later had reduced 
that gas and also oxygen to the solid condition. 


390 Beacon Lights of Science 


It was during the course of these experiments that he 
devised the Dewar Bulb, the parent of the well-known 
Thermos bottle, to hold the gases he had liquefied, and to 
keep them as long as possible in that condition. His bulb 
was a double-walled glass bottle of spherical shape, with 
a small neck aperture, the space between the walls ex- 
hausted of air to a high vacuum, and the outside silvered so 
as to reflect radiation. 

When Dewar produced solid hydrogen,.he found its tem- 
perature to be —258° C., which is within 15° ofthe absolute 
zero. Up to date all the known gases have beer reditcee 
to solids except helium. 


KOCH (1843-1910) 


BACTERIOLOGY 


Ropert Kocu was born at Klausthal, in Germany, was 
educated for the medical profession and gained an honor- 
able position in its practice. In the years between 1872 
and 1880 he became strongly interested in the subject of 
bacteriology, and decided to devote his life to it. His first 
investigations were in connection with that very fatal cat- 
tle and horse disease known as anthrax, the cause of which 
he discovered. In 1876 he published a history of the dis- 
ease so complete and so informative as to at once es- 
tablish his reputation as a bacteriologistyon a firm foun- 
dation. In 1882 he isolated the bacillus of tuberculosis, 
and for a few years thereafter it was hoped that he might 
be able to discover a cure for the disease. He did 
in fact produce a lymph for inoculation against it, but 
found its application so dangerous that he abandoned the 
effort. In 1883 he went to India to study cholera in its 
home and while there discovered and isolated the comma 
bacillus, which is the cause of the disease. After 
returning to Europe he devised a method of inoculating 
for anthrax which has proved very successful. In 1904 
he went to South Africa to study the fatal disease pro- 
duced in cattle and horses by the bite of the tsetse fly. It 


The Nineteenth and Twentieth Centuries 391 


had previously been believed that this insect was itself 
poisonous, but he demonstrated that it was simply the 
earrier of a parasite from already diseased animals. 
Those minute organisms known as bacteria, bacilli and 
microbes were first noticed by the microscopist Leeuwen- 
hoek in 1683. He regarded them as forms of animal life, 
and while his discovery created great interest at the time 
because it was believed that they represented the begin- 
nings of life of all kinds, yet the science of the day was 
not advanced enough to follow up the subject systemati- 
eally. But nearly a century later (1773) O. F. Miller 
established two genera, and fifty years thereafter Hhren- 
burg and Dujardin established a large number of them, 
which even by them were regarded as members of the ani- 
mal kingdom, and classified as among the Infusoria. This 
last is the highest and most specialized division of the pro- 
tozoa, individuals of a single cell, with apparently no or- 
gans or tissues, which are now classed as the lowest known 
forms of animal life. They are of microscopic size, and 
seem to be nothing more than particles of protoplasm, yet 
they are capable of motion from place to place. 
Bacteria, bacilli and microbes, however, are now placed 
in the vegetable kingdom. They exist almost everywhere 
in countless numbers and variety, in the air, the water and 
the soil. Also in the bodies of the living. The part they 
play in the economy of life is that of regeneration, of 
the disposal of dead tissue when that is necessary for the 
protection and prolongation of life, and of its resolution 
into its component elements after death. Thus, to them 
are due the rancidity of butter, the putrefaction of cheese, 
the gamy flavor and high odor of meat kept too long, the 
blueness and yellowness of old milk, and the changes that 
ultimately take place in very stale bread. Considered as 
a whole their work is of a beneficial nature. Millions are 
always present in the mouth, the stomach and the intestinal 
canal, and it is beginning to be understood that the numer- 
ous tooth pastes and powders that are so extensively used 
at the present time, often do more harm than good by de- 
stroying so many beneficent scavengers of the system. 


392 Beacon Lights of Science 


It was not until the middle of the last century (1853- 
1857) that their true position in natures as plants was defi- 
nitely shown. They are classed among the fungi, which 
includes all those vegetable forms (except the algae) which 
lack the power to produce chlorophyl—the green pigment 
—and hence are forced to live either as parasites on living 
plants or animals, or as saprophytes on dead organisms. 


MICHEL-LEVY (1847- ) 


GEOLOGY 


Aueustus Micue.-Levy was born in Paris, and received 
his education at the university of that city. His inclina- 
tions led him to the profession of mining engineering, and 
from that into the general field of geology, where he rap- 
idly acquired an international reputation, becoming in 
1874 the Director of the French Geological Survey, and 
the National Inspector of Mines. 

In southern France there is a region which was anciently 
the scene of intense eruptive action, in which the elevations 
known as Puy-de-Dome (4806 ft.), Mont Dore (6187 ft.), 
and Plomb-du-Cantal (6096 ft.), represent the denuded 
cones of extinct voleanos. Around these are extensive areas 
of granite, gneiss and schists, overlaid in places by overflows 
of basaltic and trachytic lavas, the whole forming one of 
the most remarkable regions in Europe from the geological 
point of view. Dykes of pegmatite, ophite and eurite are 
common, and occasional occurrences of that curious rock 
called variolite. 

Into this region he was naturally attracted, and made its 
study his specialty. He was the first to introduce the use 
of the polarizing microscope into the examination of min- 
eral structure, by cutting rocks into very thin slices, so 
that they became translucent. He led the way in the arti- 
ficial production in the laboratory of the rock forming 
crystallized minerals, such as the various feldspars, micas, 
hornblende, ete.; and was responsible for the introduction 
of the term granulite, to indicate that variety of the gneiss- 


The Nineteenth and Twentieth Centuries 393 


oid rocks which contains, in addition to quartz and feld- 
spar, minute crystals of garnet. He was a frequent con- 
tributor to the pages of the technical journals, and also a 
writer of several books on geology and mineralogy which 
are classics in their subject. His first volume ‘‘Micro- 
graphical Mineralogy,’’ which appeared in 1879, marked a 
distinct epoch in the science of minerals. It was followed 
in 1882 by ‘‘Synthesis of Minerals and Rocks,’’ and in 
1880 by ‘‘Structure and Classification of Eruptive Rocks.’’ 
In addition to these he prepared, in association with Le- 
eroix, ‘‘The Manual of Rocks’’ and ‘‘Table of Rock Min- 
erals,’’ which were published in 1888 and 1889 respectively. 

Towards the later years of his active life he undertook 
an investigation of meteorites in general, and particularly 
of specimens from the ‘‘falls’’ that had occurred in France 
in 1790, 1798 and 1803, and contributed several valuable 
moongraphs on the subject to current periodicals, which 
constitute the best general summary to date of what is 
known of the character of these bodies. Though a very 
large number have been analyzed, no new element has yet 
been found in them. They furnish no evidence of the 
existence of life on the body of which they originally must 
have formed a part. They contain no crystals except such 
as are found when a molten mass solidifies on cooling, nor 
any indication of having come into existence in a locality 
where water existed. They resemble strongly those rocks 
of terrestrial origin which are classified as igneous or 
voleanic products. They are of two kinds, ealled respec- 
tively siderites and chrondrites, which shade imperceptibly 
into each other. The former consist mainly of iron in the 
metallic state, with which nickel, cobalt, copper, tin and 
several other metals occur. The latter are of a stony na- 
ture, consisting mainly of the minerals enstatite, bronzite, 
chrysolite, ete., with which are frequently found small 
quantities of chromite, pyrrhotite and sometimes even 
graphite. 

The largest meteorite whose fall has been observed and 
proved beyond question, came to earth in Emmett county, 
Iowa, and weighed 437 pounds and was composed largely 


394 Beacon Lights of Science 


of metallic iron. Many masses weighing tons (up to twen- 
ty-five), which are believed to be of meteoric origin, have 
been found in other parts of the world, and millions of 
fragments of smaller size. The origin of these visitors 
from space is still a matter of conjecture and speculation. 
The evidence that has accumulated to date seems to indi- 
eate that the region in the solar system between the orbits 
of Mars and Jupiter, where the asteroids are located, car- 
ries also several streams of bodies, too small and scattered 
to be detected by the telescope, and moving in orbits of 
high eccentricity, parts of which come occasionally or peri- 
odically within the field of attraction of the earth, and 
terminate their long journey on its bosom, unless vaporized 
while passing through its atmosphere. 


BOLTZMANN (1844-1906) 


PHYSICS 


Lupwie BoutTzMANN, a native of Vienna, completed his 
education in the university of that city and in those of 
Heidelberg and Berlin. In 1869 he assumed the chair of 
mathematical physies at the University of Gratz, and in 
1873 that of mathematics at the university of Vienna. 
From 1876 to 1890 he was a member of the faculty at 
Gratz; from 1890 to 1895 at Munich, and from 1895 to 
1900 at Vienna. In 1900 he became connected with the 
University at Leipsic, but in 1902 was recalled to Vienna 
and continued a member of its faculty during the remainder 
of his career. 

Boltzmann took a very conspicuous part in the study of 
molecular mechanics in liquids and solids. The molecule 
is defined as the smallest particle of any given kind of mat- 
ter which retains the properties of the whole of it; as, for 
example, a molecule of water, of sulphur, of table salt. In 
the first and last of these instances the molecules are com- 
pounds in each ease of two elements, into which they can 
be readily resolved by purely chemical methods; where- 
upon, their appearances and properties as water and salt 


The Nineteenth and Twentieth Centurtes 395 


disappear, and they then give evidence of their presence 
by exhibiting the appearance and properties of those ele- 
ments (hydrogen, oxygen, sodium and chlorine) into which 
they have been decomposed. But sulphur is itself an ele- 
ment, and its molecule consists ordinarily of a union of two 
of its atoms, but under certain conditions may consist of 
six or even eight of them. Hence, if the sulphur molecule 
is broken up it still remains in its parted condition as 
sulphur. 

Molecules of all kinds, and under normal conditions, are 
constantly in motion. Those of a gas move back and forth 
in rectilinear paths which are long as compared with their 
size, and were it not for the gravitative action of the earth 
they would fly off into space and disappear. The length 
of their paths is determined by the number of them exist- 
ing in any given volume, which varies in the case of each 
known gas, and also with the external pressure under 
which it may be at the time. 

In liquids the molecules move about in all sorts of ways, 
very much like those of a bunch of live angle worms, and 
so are able to conform themselves—as a mass—to the shape 
of the vessel in which the liquid is contained. 

In a solid they are believed to be pressed so closely to- 
gether that a new foree—that of ecohesion—comes into play. 
Cohesion is perhaps simply another word for the gravita- 
tive action which, according to the Newtonian laws of mat- 
ter, every particle exerts on every other particle. These 
particles in a sold mass cohere so firmly that more or less 
force is required to separate them. Nevertheless, even then, 
it is believed that each molecule is in a state of intense 
vibratory motion back and forth along an infinitely minute 
path. If the temperature of the mass rises, these paths 
become a little longer, and exhibit the change of condition 
by the phenomenon of expansion. On the other hand, de- 
erease of temperature results in contraction, as the effect 
of the shortening of these paths. At the absolute zero of 
temperature it is believed that all vibratory motion ceases. 

It was into the field of these phenomena that Boltzmann, 
equipped with high mathematical ability, made deep ex- 


396 Beacon Lights of Science 


ploration, using data already well demonstrated in the sci- 
ence of mechanics to light his path. For a time it was 
thought that he had secured some results of importance. 
But since the announcement of the quantum theory of 
Planck these expectations are not so strong, and some re- 
vision of his conclusions appear to be inevitable. 


METCHNIKOFEF (1845-1916) 


BIOLOGY 


IntvA METCHNIKOFF was born in the vicinity of the town 
of Kharkov in southern Russia, and after receiving his 
primary education in the schools of that city, took special 
courses in natural history and physiology at the universi- 
ties of Giessen and Munich in Germany. He was then 
appointed professor of zoology at the University of Odessa, 
and after serving there seven years, resigned to devote 
himself to research in the domain of sponges and coral 
polyps. In 1884 he published the result of his investigations 
on these low forms of animal life, in the course of which 
he announced the discovery that the individual cells of 
these organisms possessed the power of seizing, absorbing 
and digesting solid particles of food, and of excreting such 
parts of it as were unsuitable for their purposes of nour- 
ishment and growth. He called the phenomenon—which 
had not before been observed—‘‘intercellular digestion.’’ 

Following up this important lead, he soon afterwards 
detected and described those remarkable cells residing free 
in the blood: of all animals which are known popularly as 
the white corpuscles, and technically as ‘‘phagocytes.”’ 
These are living organisms, whose function in the body is 
to destroy (by the process of eating and digesting) injuri- 
ous or poisonous microbes and germs which may have 
gained access to the circulatory system, or the tissues, by 
accident or design, and which, if not removed or in some 
way counteracted, would produce disease and ultimately 
death. 

Led by these observations—which he watched in progress 


The Nineteenth and Twentieth Centuries 397 


under the microscope—he advanced the theory which has 
since been amply confirmed, that the well-known phenome- 
non of inflammation that invariably accompanies bruises 
and wounds in all animals and man, is due to the struggle 
that at once ensues between these white corpuscles and 
the disease germs that immediately attack the body at any 
place where the continuity of the protecting skin is broken. 
When such an injury occurs, new blood well charged with 
these phagocytes (eating cells) is at once sent by the heart 
to reinforce the protective army at the point of injury. 
This causes a wholesome congestion there, and the inflam- 
mation condition continues until either the invaders are 
destroyed and the wound healed, or the loss of blood be- 
comes so great that the heart is unable to supply any more, 
and death ensues. 

This discovery was considered of so much importance by 
biologists and physiologists, that in 1892 Metchnikoff was 
invited to come to Paris, and was offered the position of 
chief assistant to Pasteur. At the death of the latter in 
1895 he succeeded him as Director of the Pasteur Insti- 
tute, and remained its head through the balance of his life. 


WROBLEWSKI (1845-1888) 


PHYSICS 


ZYGMUNT FLORENTY WROBLEWSKI was born at Grodno 
in Poland, when that part of it was a provinee of the Rus- 
sian Empire. He was of pure Polish ancestry. While a 
student at Kiev he took part in the insurrection of 1863, 
and was banished to Siberia. Six years later he was par- 
doned and resumed his studies, which were finally com- 
pleted by taking special courses at the universities of Ber- 
lin, Heidelberg and Munich, at the last of which he received 
his degree, and became an assistant in its physical labora- 
tory. Subsequently he served as lecturer and assistant 
lecturer successively at the Universities of Strassburg, 
Paris, London, Oxford and Cambridge, and finally in 1882 
was appointed professor of physics at the University of 


398 Beacon Lights of Science 


Cracow in his own home land, where he remained as a 
member of the faculty of that ancient institution until his 
death. 

Although a brilliant and interesting speaker, with the 
command of several languages besides Russian and his own 
mother tongue, he is best known for his work on the lique- 
faction of gases. The first of the physicists to take up this 
important subject was a Belgian chemist by the name of 
Van Helmont, who attained some prominence about the 
year 1590, and who was responsible for the introduction of 
the word ‘‘gas’’ into technical use. He made a distinction 
between it and the word ‘‘vapor,’’ using the latter for 
those that could be condensed into the liquid state, like 
steam, and the former for those that could not, like air. 
Dalton was the first to assert that all gases could be lique- 
fied by the application by the proper degree of pressure 
and temperature. Faraday took the first steps towards 
the realization of this belief, and succeeded in liquefying 
chlorine, carbon dioxide, sulphur dioxide, cyanogen and 
several others, in fact, all then known except hydrogen, 
oxygen, nitrogen, nitric oxide and marsh gas. Andrews, 
in 1869, advanced the theory that for each gas there was 
a certain temperature and pressure which must be reached 
simultaneosuly, to secure liquefaction. With this new light 
on the problem, oxygen was reduced to the liquid state in 
1877 by Callitet and Pictet, and in 1883, by employing 
improved methods and apparatus, Wroblewski and Olszew- 
ski at Cracow accomplished the transformation in quantity 
of oxygen, nitrogen and carbon dioxide, and reduced the 
last two to the solid condition. Since then Dewar and 
Onnes have completed the work with all known gases except 
helium. 

The accomplishments of Wroblewski while spectacular, 
were also of great service indirectly, by giving physicists 
the command of a new tool—low temperature. With it 
much more correct determinations of specific heat become 
possible, and in several other directions some rather unex- 
pected results are likely to accrue. For instance, it has 
already been shown that under a pressure of 300,000 


The Nineteenth and Twentieth Centuries 399 


pounds per square inch, water will become a solid at a 
temperature 73° C. higher than its normal or usual freez- 
ing point. 


ROENTGEN (1845-1922) 


PHYSICS 


WILHELM KonrAp ROENTGEN was reared at Lennep in 
East Prussia, and received his doctor’s degree at the Uni- 
versity of Zurich, where he specialized in physics. After 
occupying subordinate professional positions at the schools 
in Hohenheim, Strassburg, Giessen, and Wurtzburg, he 
was appointed to the chair of experimental physics at the 
University of Munich, a position which he held during the 
remainder of his active life. 

He was the discoverer (in 1895) of the X-rays, which 
brought him honors from institutions of learning through- 
out the world. The rays were so called by himself because, 
for some time, he was unable to explain them. They are 
now very properly known as the Roentgen rays, and are 
better understood. To produce them, a Crooke’s tube is 
employed. This is a sealed tubular or globular glass vessel, 
from which the air has been withdrawn. Into its ends or 
sides have been sealed metallic conducting wires, connected 
with a source of the electric current. The incoming or 
positive current wire, may or may not be fitted with a 
small metal plate at its inside termination, and is called 
the anode. The other, by which the current leaves the 
tube, carries at its end a small concave metal plate, the 
coneavity being turned towards the interior. This is called 
the cathode. When a current of electricity is passed 
through the apparatus, aside from the glowing effect pro- 
duced, certain rays originate on the cathode plate which, 
being brought to a focus on the inside of the tube, pass 
through the glass. These are the Roentgen rays, and have 
very remarkable properties. They appear to be capable 
of passing through nearly all substances, but not with equal 
ease or speed, dense substances being less permeable than 


400 Beacon Lights of Science 


less massive ones. They also have the power of chemically 
acting on the sensitive photographic plate or film. As they 
pass freely through living flesh, but less freely through the 
bones, or any dense metallic or other substance, it became 
possible to make shadow photographs of the living body, 
in which the bony skeleton or any other body less permeable 
than the flesh, appears as shadows, while the normal fleshly 
outline of the figure is revealed as a much fainter shadow. 
This discovery has proved of great value in the surgical 
art, particularly in eases of bone fractures or displace- 
ments, or bullet wounds, and also of abnormal growths 
(tumors) in the tissues. 

The exact nature of the Roentgen rays is still unex- 
plained. Their discoverer received the Nobel prize for 
physics in 1901, and was elevated to the nobility by the 
German government. 


EDISON (1847-__) 


ELECTRICITY 


THomaAs A. Epison was born at Milan, Ohio. ‘At the age 
of seven his parents moved to Port Huron, Michigan. Here 
he secured the rudiments of an education, but was forced 
to get out into the world at an early age and earn his 
living. After working for a time as a train news agent 
on the Grand Trunk R. R. and simultaneously conducting 
a small newspaper enterprise, he turned his attention to 
telegraphy, quickly became a Morse-key expert, and easily 
secured the position of night operator at his home town. 
Having become interested in chemistry through the reading 
of books on that science, he was allowed by his parents to 
fit up a laboratory in the attic of the house they occupied, 
where he carried on his experiments during the day, in- 
stead of getting enough sleep to fit him properly for his 
employment at night. In consequence he soon lost his 
position by being caught asleep on duty. He then entered 
upon the life of a wandering telegraph operator, passing 
from one situation to another without difficulty, for at the 


The Nineteenth and Twentieth Centuries 401 


time there was a great demand for experts at the key. Af- 
ter several years of that kind of life in what is now the 
Middle West, he drifted eastward, finally landing in Bos- 
ton, and had the good fortune there to get hold of a copy 
of the works of Faraday, which impressed him deeply. In 
that city he made his first invention—a vote-recording ma- 
chine for use in legislative bodies. 

From Boston he went to New York, still in the char- 
acter of a wandering operator, and continually short of 
money because his surplus earnings were spent as fast 
as they accumulated in books, experiments in chemistry 
and electricity, and in models of inventions. There, in 
1869, he perfected certain improvements in stock tickers, 
which brought him quickly a considerable amount of money, 
some $40,000, and with it he opened a laboratory in Newark 
and began the manufacture of the numerous electrical de- 
vices which his fertile brain had conceived. But soon find- 
ing himself in financial straits because these did not sell 
fast enough, he called one day at the office of Dr. Norvin 
Green, the president of the Western Union Telegraph Co., 
to try to interest him in his patents. He found the doctor 
endeavoring to get into telegraphic communication with 
Albany. There was trouble somewhere along the line, and 
no one seemed to be able to locate the place or the cause. 
Edison asked to be allowed to solve the problem, and in 
two hours had located the difficulty within a few miles. 
Green was so impressed with the performance that he not 
only gave the young man the hearing he sought, but when 
it was concluded advanced the money Edison needed to 
relieve his financial difficulties and took an interest in his 
plant on behalf of his company. For it Edison invented 
and put into practice, in turn, his automatic duplex and 
quadruplex systems of telegraphy, by the latter of which, 
on one wire, two messages in each direction could be sent 
simultaneously, and recorded at the receiving end on chemi- 
cally prepared paper, at the rate of 3500 words per minute. 
For these he was handsomely compensated. 

Now at last in comfortable circumstances, he turned 
his attention from telegraphy to telephony. By then A. 


402 Beacon LInghts of Science 


Graham Bell had demonstrated the practicability of the 
latter, had devised an excellent receiver, but his transmit- 
ter was unsatisfactory. The Western Union Co. was back- 
ing him and ealled in Edison. The latter in a short time 
produced his carbon transmitter, which is in use at the 
present time, and sold it to the Company for $100,000. 
Shortly afterwards he perfected his electromotograph 
which brought him $250,000 for the American and Eng- 
lish rights alone. 

His next notable accomplishment was the production 
of the phonograph in 1877. When the first crude model 
had been constructed, the words spoken into it, and re- 
peated from it, were those of the first verse of the familiar 
nursery rhyme ‘‘Mary had a little lamb,’’ and the voice 
was that of Edison himself. 

In the following year he turned his attention to the elec- 
tric light. The are light had already been invented, and 
put into practical use to a considerable extent for highway 
illumination. But it was too expensive, too brilliant and too 
noisy for interior use. In its stead Edison proposed and 
perfected the familiar small glass globe, exhausted of its 
air, and fitted with the now nearly forgotten carbon fila- 
ment heated to ineandeseence. The first one devised, which 
was made of cotton thread, lasted only 40 hours. After a 
large number of trials of other materials, one that was con- 
structed of bamboo fiber of a particular variety, stood the 
test and strain put upon it long enough to make the discov- 
ery commercially practical. From this beginning has 
sprung the highly perfected tungsten filament bulbs of the 
present day, which are in use by the hundred of millions 
throughout the world. 

Of his many other inventions he most notable has been 
the cinematograph (first known as the vitaseope), which 
was perfected less than twenty years ago. Others of note, 
though less well known, because of their limited fields of 
employment, are the alkaline storage cell and the magnetic 
ore separator. He was the discoverer of a method of 
making carbolie acid synthetically; and when the Great 
War broke out, cutting off the supply from Europe, he 


The Nineteenth and Twentieth Centuries 403 


built a factory for its manufacture in an incredibly short 
time. Altogether he has taken out more than a thousand 
patents. 

A man of tireless energy, and a sufferer from early man- 
hood under the handicap of deafness, he has maintained 
throughout his maturity, and carried into his green old 
age, the individuality and the simplicity which is typically 
the heritage of the American. His name is a household 
word in all parts of the civilized world. In his own coun- 
try he has been awarded by popular vote the title of its 
first citizen. Plain in manner and dress, and pithy in 
speech, his definition of genius as ‘‘one per cent inspiration 
and ninety-nine per cent perspiration’’ epitomizes his life 
and career perfectly. 


ROWLAND (1848-1901) 


PHYSICS 


Henry Avucustus RowLAND was born at Honesdale, 
Pennsylvania, and graduated in 1870 at the Rensselaer 
Polytechnic Institute at Troy. In 1876 he was elected to 
the chair of physics at the Johns Hopkins Institute in 
Baltimore, and held that honorable position for the re- 
mainder of his life. 

His reputation rests upon several achievements. By far 
the most important of these was the introduction of im- 
provements in spectroscopic apparatus, which enabled him 
and others to reach accurate results in the measurement 
of the wave lengths of the spectral lines produced by the 
elements when heated to incandescence. At the time these 
were regarded as new and most interesting data, but of 
little practical use. Since his death, however, they have 
proved to be of extraordinary value in the study of the 
nature of the chemical atom, which is perhaps the outstand- 
ing achievement of the physicist of the present day. His 
improvement consisted in the discovery of the principle 
of the spherically concave reflecting grating, and the con- 
struction of a machine for drawing lines upon it so ex- 


404 Beacon Lights of Scrence 


tremely close to each other, that fifteen thousand of them 
could be placed side by side within the space of an inch, 
and at exactly equal distances apart. When on such a sur- 
face—ealled a reflecting gratine—a ray of light is thrown, 
the phenomenon ealled diffraction occurs. 

Diffraction was first observed in 1665 by Grimaldi, an 
Italian landscape painter. It consists of the appearance on 
the edges of a shadow cast by an opaque body upon a 
sereen, of a very narrow band of colors, so narrow in fact 
as to be almost unnoticeable unless very carefully looked 
for. It was also observed and studied by Newton, but as 
he was the originator of the corpuscular theory of light, 
and held that its rays moved in absolutely straight lines, he 
was unable to account for it. Fresnel, however, in 1819, 
correctly explained it by showing that it was an effect 
resulting necessarily from the undulatory character of light 
waves which, in passing the sharply defined edge of an 
opaque body, would be slightly bent inward, and to an 
extent proportional to the amplitude (distance from crest 
to erest) of the wave. As this dimension for the wave of 
each color differs, some of them would be bent more than 
others, and the combined result would be the narrow band 
of colors always to be found under the conditions stated. 

Rowland made an exceedingly accurate measurement of 
the mechanical equivalent of heat; and of the value of the 
ohm, the electrical unit of resistance. His study of the 
magnetic properties of iron led to entirely new conceptions 
of the nature of magnetism. For his development of a 
system of multiplex telegraphy, he received the gold medal 
of the Paris Exposition of 1881. At the time of his death 
he was the president of the American Physical Society. 
He was a large contributor to technical publications, both 
in the United States and Europe. His collected physical 
papers, together with a biography, were published in 1902 
by the Johns Hopkins Press. 


The Nineteenth and Twentieth Centuries 405 


MOISSAN (1852-1907) 


CHEMISTRY 


Henri Moissan was a native of Paris, and after passing 
through the College of the Museum of Natural History, he 
joined the faculty of the School of Pharmacy, becoming 
professor of toxicology in 1886, and of mineral chemistry 
in 1889. 

Becoming greatly interested in 1886 in the gaseous ele- 
ment fluorine, he was the first to isolate it, to reduce it to 
the liquid state, and to ascertain its properties. As fluorine 
is the most active, chemically, of all the known elements, 
and requires for its liquefaction a reduction of temperature | 
to — 187° C. the accomplishment was a most notable one, 
and brought him the Lacaze prize in the following year. 
In 1894 he succeeded in making artificial diamonds, by the 
sudden cooling of molten iron that had been impregnated 
with carbon, but the crystals so produced, though perfect, 
were too minute to have any commercial value. 

He also devised, and put into operation, a greatly im- 
proved process for the manufacture of acetylene gas. For 
these, and other researches in applied chemistry, he was 
awarded the Nobel prize in 1906. 

The isolation of fluorine was an achievement of note be- 
cause the intense chemical activity of the element compels 
it, when driven out of any compound of which it is a con- 
stituent (like fluorspar) to unite violently with almost any 
other that may be available. At normal temperatures it is 
a pale yellowish gas, with an unpleasant odor, and if put 
into a glass bottle will at once begin to eat its way out by 
decomposing the glass. In fact, about the only substances 
of which containers can be made that will hold it are lead, 
gutta percha, paraffin and the two minerals fluorspar and 
eryolite, of which it is already a part; the former being the 
fluoride of calcium, and the latter the fluoride of sodium 
and aluminum. Fluorspar is quite abundant in nature but 
eryolite is rare, the only deposit of size that is known being 
in Greenland. 


406 Beacon Lights of Science 


In spite of its violent propensities, and in fact because of 
them, the element when combined with hydrogen in the 
form of hydrofluoric acid, has many uses in the arts. If 
a piece of glass is covered with a thin layer of mineral 
wax, and figures drawn upon the new surface so as to re- 
move the wax along their lines, and the plate then exposed 
over a vessel containing this acid, and the latter gently 
heated, the fluorine will temporarily abandon the hydrogen 
and attack the exposed glass surface and lines, seize upon 
its silicon, carry their molecules back to the forsaken hydro- 
gen, and unite again with it to a new compound called 
hydrofluosilicie acid. By this process all the well-known 
varieties of opalescent glass are produced. The action is 
known as etching. Porcelain of the densest kind may be 
etched the same way. The wax and the other protective 
substances mentioned do not seem to possess any attraction 
for the gas. But if allowed to meet antimony, arsenic, 
boron, iodine, silicon, or sulphur, so intense is its affinity 
for them, or they for it, that the heat produced in the 
reaction will cause all of them to burst violently into flames. 


FISCHER (1852-1919) 


CHEMISTRY 


Emit FiscHER was born at Euskirchen in Germany, was 
educated at the University of Strassburg, and in 1879 was 
appointed to the chair of chemistry at the university of 
Munich. In 1882 he was transferred to a similar post at 
Erlangen and in 1885 the same at Warburg. In 1892 he 
took the professorship of organic chemistry at the Univer- 
sity of Berlin, where he remained for the balance of hls 
active career. 

His specialty was synthesis, and his principal work was 
on the sugars, where he achieved remarkable success. He 
began his work on these in 1883 when almost nothing was 
known of their nature except their chemical composition. 
By 1908 when his work had been completed and its results 
published, he had been able to produce them all syntheti- 


The Nineteenth and Twentieth Centuries 407 


eally, and had determined the molecular structure of each 
kind. In the course of this very important work, the the- 
ories of stereo-isomerism that had already been advanced 
by Van’t Hoff were confirmed and systematized. He also 
succeeded in producing synthetic caffeine, the alkaloid 
which is the active flavoring constituent in coffee, and made 
remarkable progress in the study of the proteins, sueceed- 
ing, before he was compelled to abandon the work, in the 
synthetic preparation of the peptides, the active principle 
in the gastric juice, which has the property of converting 
the protein elements in food into peptones, a condition in 
which they are digested, and are then capable of assimila- 
tion by the rest of the alimentary system of the body. These 
discoveries were considered of such importance, that in 
1902 he received the Nobel prize of $40,000 for distin- 
guished services in chemistry for that year. 

Those pleasant tasting vegetable products which are 
known as the sugars are a most interesting class of sub- 
stances. In very olden days honey was the only variety 
known, and was so rare and valuable as to be procurable 
only by the wealthy; but in the time of Grecian national 
supremacy something became known in that country of the 
sugar cane, which seems to have been indigenous in India 
and southern China, and from which was extracted a coarse 
and crude product that by Arab traders was brought in 
small quantities to Greece under the name of ‘‘sukkar,’’ 
and eagerly accepted in trade. When that brilliant na- 
tionality gave way to Roman rule, the knowledge appears 
to have been completely lost. But during the Crusades 
(1096-1272), samples of the cane extract were again en- 
countered among the Arabian holders of the Holy Land, 
and finally the plant itself was introduced in Sicily and 
southern Spain, and from there gradually spread into other 
parts of the semi-tropical world. In 1747 a German chem- 
ist by the name of Margeraff called the attention of the 
Berlin Academy of Sciences to a variety of the beet which 
contains a notable percentage of sugar, and from which, a 
half century or so later, a pupil of his named Achard, 
succeeded in extracting enough of it to interest both Ger- 


408 Beacon Lights of Science 


man and French capitalists in its cultivation on a large 
scale. Since then the industry has expanded enormously, 
for the beet flourishes in temperate climates, and the plant 
has now been so greatly improved that its sugar content, 
originally less than 7 per cent, has been raised to 16 and 
18 per cent. 

There are many different varieties of sugar. All consist 
only of the three elements, carbon, hydrogen and oxygen, 
but not always combined in the same proportions. Cane 
and beet sugar, when prepared with equal care, are identi- 
eal, and are represented in chemical language by the for- 
mula C,,H.,,0,,, which simply means 12 parts of carbon, 
22 of hydrogen and 11 of oxygen. Maple sugar and honey 
when pure are almost the same, but each contains certain 
additional ingredients to which they owe their distinctive 
flavor. Glucose, however, is not sugar, for though it has 
a sweet taste, and is the substance which produces the pleas- 
ant sweetness of the fruits, its formula is C,H,,0,. Curi- 
ously enough, while the true sugars are perfectly assimi- 
lated by the animal organism, glucose is not, but passes 
through the system without conferring advantage either in 
building up muscular tissue or adding energy. On the 
other hand, it is an ideal plant food, and has been advan- 
tageously employed in certain cases as a fertilizer. 


RAMSAY (1852-1916) 


CHEMISTRY 


WILLIAM RAMSAY was a native of Glasgow, Scotland, ac- 
quired his early education there, and took his doctor’s de- 
gree at the University of Tubingen, in Germany, at the 
age of twenty. From 1880 to 1887 he was professor of 
chemistry at the University of Bristol, and then took the 
chair in the same science at the London University. Here, 
working in association with Baron Rayleigh, they discov- 
ered in 1894 the gaseous element argon. In the following 
year, while working on the mineral clevite—a sample of 
which had been received from Norway-—they extracted 


The Nineteenth and Twentieth Centuries 409 


from it, and isolated, the element helium (also a gas at 
normal temperatures). This element had been detected 
spectroscopically in 1868 in the solar chromosphere, by the 
astronomer Lockyer, Its discovery on the earth, as a com- 
ponent of a well-known, though comparatively rare min- 
eral, was an event of the very first importance in the sci- 
entific world. 

In 1898 Ramsay detected, and isolated from the atmos- 
phere, three additional new gaseous elements, to which he 
gave the names of krypton, neon and xenon. 

The discovery, isolation and investigation of these five 
elements, marked a distinct and very notable step in the 
progress of the science of chemical physics. All are abso- 
lutely inert, refusing to react with each other, or with any 
of the other elements. To accommodate them in the Peri- 
odie Table of the elements (see Mendeleef), a new vertical 
series had to be inserted, which, however, instead of disar- 
ranging the system, had the effect of rendering it still more 
complete. 

In the few years that have elapsed since this noted in- 
vestigator died, so much has been learned of the nature of 
the chemical atom, that it is now possible to account for 
the inertness of these five gases and, as usual, when the 
explanation was reached, it was found to be of that simple 
nature which experience has taught us to expect in ulti- 
mate facts. It is now demonstrated that there must be 
at least 92 chemical elements or units of matter, of which 
some eighty-eight have so far been discovered and their 
properties more or less ascertained. There may be more, 
but for reasons that will be given it is not considered likely. 
At the top of the list is the gas hydrogen, the lightest sub- 
stance known and the simplest in structure. At the bottom 
is the metal uranium, the heaviest and the most complex 
in composition with which the physicist is acquainted. Be- 
tween these two, each in its own pigeon hole in the periodic 
system of Mendeleef are the others, listed according to their 
relative weights on the basis of 16 for oxygen. Appar- 
ently the most stable of them all is the gas hydrogen, being 
composed of just one proton and one electron; while the 


410 Beacon Laghts of Science 


last three of the list (radium, thorium and uranium) are 
very unstable. For this reason it is believed that no more 
of greater weight can exist, for these, as a direct conse- 
quence of the complexity of their structure, are in a chronic 
state of falling into pieces. 

Since this limitation in probable number has been recog- 
nized, and since the atom of each has been shown to be 
a mathematically arranged collection of those infinitely 
minute units of electrical force called protons and electrons, 
and since the number of these in each kind of atom has 
been definitely ascertained, it has been found that the inert 
gases are the only ones so structurally composed as to have 
acquired what might be called as a condition of perfect 
symmetry. They are elements so shapely, so organized as 
to the number and disposition of the protons and electrons 
of which they are composed, that they may be considered 
the aristocrats of the tribe, each one quite indifferent to all 
the others, even those of its own very limited class. The 
rest are more or less unsymmetrical in shape or unsatisfied 
in the matter of the disposition of their electrical units, 
and constantly exhibit an inclination either to pass some 
of their superfluous ones over to an element residing in 
another pigeon hole of the system, or to grab some of those 
possessed by another one. As the law of their existence so 
far as at present ascertained prohibits such inter-elemen- 
tary gifts or thefts, their only alternative is to come out 
of their pigeonholes and form partnerships, when inclina- 
tion and opportunity occurs to do so. This process is con- 
stantly going on in the world of matter. Those that have 
taken place in the realm of inorganic things are compara- 
tively stable affairs, for quite an amount of force must be 
applied to break them up. But in the organic realm, that 
of vegetable and animal life, the change of partners is con- 
stantly in progress, quite as much after the arrival on the 
scene of the phenomenon we eall death, as before its ap- 
pearance. But through it all the inert gases stand haughtily 
aside from the bustle and turmoil, refusing to take any 
part in it, or even to be friendly and chatty among them- 
selves. The amount of them in nature is extremely small, 


The Nineteenth and Twentieth Centuries 411 


but already a use has been found for the lightest (helium), 
and if aviation is going to fulfill the promise of its youth- 
ful days a lot of it is sure to be demanded before long. 
There has also been found a field for the employment of 
one or more of the others in illumination. In fact inert- 
ness and unsociability has some few advantages in the 
world of the applied sciences as it has in social matters. 


BECQUEREL (1852-1891) 


PHYSICS 


ANTOINE HENRI BECQUEREL was a native of Paris, being 
educated at the Ecole Polytechnique, and the Ecole des 
Ponts et Chaussées, from the latter of which he graduated 
in 1877 as an engineer. In the following year he became 
professor of physics at the Museum of Natural History, 
from which he passed, in 1895, to the same post at the Ecole 
Polytechnique. He became a member of the Institute in 
1889. 

He devoted himself during his career in a large degree 
to the phenomena of optics and phosphorescence, branching 
out into spectroscopy, and the effects of magnetism on 
polarized light. His most important discovery—made in 
1896—and the one which brought him the Rumford medal 
of the English Royal Society, was that of the invisible rays 
which he found were emitted from ores of the metal 
uranium, and were capable of affecting the sensitized photo- 
graphic plate. As these rays did not obey the known laws 
of light, and proved to be able to penetrate many bodies 
that are opaque to light, the greatest interest was excited 
in scientific circles by their discovery; which was height- 
ened when, two years later (1898), the new element radium 
was shown by M. and Mme. Curie, to be the component 
in the ore that produced them. Thus, while Becquerel is 
justly entitled to the credit of having been the first de- 
tector of this new form of radiation, to the Curies belong 
the honor of ascertaining its origin, and of inaugurating 
the entirely new department of physical-chemistry or chem- 


412 Beacon Lights of Science 


ical-physics, which has for its field not only the evolution 
of the elements, but their devolution, or decomposition. 

Radium is believed to be a metal, though it has not yet 
been isolated. But its position in the Periodic System of 
Mendeleef, and the behavior of such of its salts as have 
been produced—mainly the chloride and bromide—strongly 
indicate the metallic characteristics. Since its discovery an 
enormous literature in radio-activity has come into exis- 
tence, and the subject is by no means exhausted as yet. It 
belongs to the vertical group that begins with beryllium 
and continues with magnesium, calcium, zine, strontium, 
cadmium and barium, followed by two uncertain ones, and 
mereury, with radium as the last member; and in the 12th 
horizontal series, along with thorium and uranium. These 
three are respectively the 89th, 91st and 92nd in the list 
of the elements, and are of such high atomic weight, —226.4, 
232.43 and 238.5 respectively, and possess such complicated 
atomic structure, as to be steadily undergoing the processes 
of devolution or breaking up into elements of lower atomic 
weight and greater stability. 

Becquerel’s discovery, followed by that of the Curies, 
furnished the key which has since unlocked the mystery of 
the chemical atom, and made it plain that matter, as the 
word has theretofore been understood, is no longer an en- 
tity. It is simply one of the manifestations by which the 
all-pervading energy of the Universe makes itself known to 
our senses. 


VAN’T HOFF (1852-1908) 


CHEMISTRY 


JAKOBUS HENDRIKUS VAN’rt Horr was born at Rotter- 
dam, Holland, and studied in turn at the universities of 
Delft, Leyden, Bonn, Paris and Utrecht, after which he 
became an assistant instructor in 1876 at the last named in- 
stitution. Here he displayed so much ability that in 1878 
he was called to the chair of chemistry and physies at the 
Amsterdam University from which he passed in 1896 to the 
Same position at the University of Berlin. 


The Nineteenth and Twentieth Centuries 413 


In addition to having taken a high rank among recent 
investigators in the field of physics, his great contribution 
to the advance of knowledge consisted in important dis- 
eoveries in the domain of stereo-chemistry, that branch of 
the science which has to do with those quite numerous cases 
of isomerism—substances identical in chemical composition 
but displaying different properties under certain optical 
and other influences—which cannot be explained under the 
doctrine of the linking of the atoms. As to these, he 
reached the conclusion in 1874 (which has since been amply 
corroborated) that all optically active compounds—and 
only such—contain one or more asymmetric carbon atoms 
or groups of atoms differing from one another. Several 
years later he succeeded in working out a theory of geo- 
metrical isomerism, which to date has been found capable 
of making clear all the phenomena so far observed in this 
department of research, which has now become an impor- 
tant branch of applied science. It was originally confined 
only to compounds of carbon, but has since been extended 
into those of nitrogen. 

The department of physical chemistry is a comparatively 
recent addition to the roster of the sciences; but one that 
has become necessary to cover those many phenomena along 
the boundary between physics and chemistry that have 
arisen for consideration by the students of both. A few 
of these are, molecules and molecular weights, solutions, dis- 
sociation, thermo-chemistry, electro-chemistry, photo-chem- 
istry, evaporation, distillation, freezing, melting, boiling 
and critical temperatures. Van’t Hoff was regarded while 
living as its chief apostle, and certainly has done more than 
anyone else so far to raise it to the position of an inde- 
pendent branch of research. He was also the originator of 
the following generalization, which appears to be true in 
all departments: 

‘Whenever any change of any kind in the realm of 
Nature can accomplish work, that is, overcome resistance, 
it must proceed when the resistance is absent.”’ 

Shortly before his death he advanced a theory for ex- 
plaining the space relations of the atoms in the molecules, . 


414 Beacon Lights of Science 


which appears to give a correct answer to many questions 
where uncertainty existed, and which ultimately may afford 
a clearer insight into the as yet unsolved mystery of mag- 
netism. But it must stand further critical tests before it 
will receive general acceptance. 


THOMSON (1856-1907) 


ELECTRICITY 


JOSEPH JOHN THOMSON was a native of Manchester, 
England, and was educated at Owens College in that city, 
and at Cambridge, graduating from the latter in 1880. 
Four years later he became professor of experimental 
physies there, and remained in connection with that great 
institution of learning for the balance of his active life. 

His special field of study and research was that of 
physics, where he made a number of brilliant discoveries. 
To him, more than to anyone else during his lifetime, is 
due the development of the ionic theory of electricity, and 
the electrical theory of the inertia of matter. Huis papers 
on. these subjects, as also on radio-activity, have been epoch 
making. 

The ionic theory of electricity as enunciated by him was 
to the effect that a current of electricity consisted of the 
motion of minute particles of matter which he ealled ions, 
each of which carried a charge of either positive or nega- 
tive electricity, the movement of the oppositely charged 
particles being in opposite directions. These particles, how- 
ever, were not molecules. He believed that ions were al- 
ways present in all solid conductors, but not always in 
motion, in fact, were in motion cnly when a current was 
initiated from some external source. In liquids he thought 
that ions were brought into existence by dissolving in it 
some salt or acid that underwent the process called disso- 
ciation. This is a chemical process which, in the solid state, 
is illustrated in the familiar operation of transforming lime- 
stone—a combination of the oxide of the metal calcium 
with the gas carbon dioxide—by burning it in a kiln. When 


The Nineteenth and Twentieth Centuries 415 


the proper temperature is reached the gas lets go its hold 
on the calcium oxide and the latter becomes quicklime, a 
substance so eager to find something to replace its former 
partner, that when water is offered it is accepted with 
avidity and the production of a considerable quantity of 
heat. An example almost equally familiar of the process 
in a liquid is that of ammonium chloride, commonly called 
sal ammoniac, consisting of a union of ammonia with hydro- 
chlorie acid. When this substance—which can exist in 
both the solid and the liquid state—is, in the latter, gently 
heated, the ammonia will release itself from the grasp of 
the acid and pass away. But if, in both these examples, 
the operation is carried on in a vessel so constructed that 
pressure can be applied at will; then, if it is applied after 
the process of dissociation is well under way, the two gases 
mentioned will go back to their former associates. It is 
impossible to transform limestone into quicklime in a 
closed vessel like a retort, no matter how high a tempera- 
ture is employed. 

Electrieal dissociation as conceived by Thomson was a 
somewhat similar yet wholly different phenomenon, and it 
should here be remembered that while chemical dissociation 
is a well-demonstrated fact, the other was merely suggested 
by him as a theory to be proved or disproved by further 
investigation. According to it, when certain acids or salts 
were dissolved in water they became capable of breaking 
up (without the application of heat) into atomic groups, 
if provoked to do so by the attempted passage of an electric 
current through them, and when disruption of that kind 
was effected each atom so isolated carried, he thought, either 
a positive or a negative electrical charge, In consequence 
of which it became capable of transporting the electrical 
current and was an electrolyte. As an example, take the 
case of common table salt, a compound of the metal sodium 
and the gas chlorine. Ag ordinarly known it is a white 
grainy solid. Upon the addition of water it becomes a 
transparent liquid with a briny taste. In this state it was 
capable under his theory, when properly provoked, to dis- 
sociate into its atomic constituents, each then acquiring an 


416 Beacon Lights of Science 


electric charge, that of the metal being of the positive kind, 
and of the gas the negative, these then becoming ions. 
Since Thomson’s day the fact of this ionic dissociation 
has been amply demonstrated, but the cause of it has been 
shown to be different from that suggested by his theory. 
The elementary atoms which then were believed to be the 
ultimate forms of matter, are now known to be simply 
groups of electrons and protons, which themselves appear 
to be the ultimate forms of force. Thus, in the few years 
that have passed since his theory was advanced matter, as 
understood by every body in his day has totally disap- 
peared. It is no longer proper to speak of the atom of 
sodium—for instance—as carrying a _ positive electric 
charge, or of the atom of the gas chlorine as carrying a 
negative electric charge, for in each case the atom and its 
assumed charge are identical, or one and the same thing. 


HERTZ (1857-1894) 


PHYSICS 


HermricH Hertz spent his early years in Hamburg, 
Germany. After obtaining a good primary edueation, he 
began the study of civil engineering; but finding the pro- 
fession uncongenial, he turned to mathematics and the sci- 
ences, becoming finally in 1880 an assistant to Helmholtz 
at the University of Berlin. In 1883 he undertook tutor- 
ing work at the University of Kiel, and in 1885 was elected 
to the chair of physics at the Polytechnic Institute at 
Karlsruhe. Here, at last, he had the opportunity to carry 
on his investigations on electro-magnetic waves, and his 
discoveries in regard to them were so important and re- 
markable, that he was called to the chair of physics at the 
University of Bonn in 1889, a position which he held dur- 
ing the remainder of his brief life. 

To Hertz is due the discovery of those electro-magnetic 
waves in the ether, which have made possible the sciences 
of radio telegraphy and telephony. These pulsations are 
known as the Hertzian waves. They can be propagated 


The Nineteenth and Twentieth Centuries 417 


by the spark of an electrical machine, can be received on 
a wire made of a metal with good conducting properties, 
by the latter can be propagated into space in the form of 
pulsations which may be caught up again on another wire 
at a distance, and by it carried into a receiving device, 
where a duplicate of the original impulse may be repeated 
and made audible. 

Hertz demonstrated that these undulations, like those 
which produce the sensation of light, can be reflected, re- 
fracted, diffracted and polarized. 

Because it is quite impossible to imagine motion unless 
there is something capable of being moved; when the phe- 
nomenon of light was found to consist of waves or undula- 
tions, it became necessary to assume that the space between 
us and the sun and stars was not empty of all substance as 
had been believed, but must be filled with some material 
capable of vibrating and of transporting to us those move- 
ments which constitute light, heat and the effects produced 
by the other kinds of ‘‘rays’’ now known, the actinic, the 
Beequerel, the Roentgen and the Hertzian. To supply this 
deficiency a medium was assumed, and given the name of 
the ether, originally written ether, because derived from 
the Greek word ‘‘aitherios,’’ which to them meant the 
upper air or, In general, the blue heavens that were sup- 
posed to extend to the sun, the planets and the fixed stars. 

All attempts to date of modern scientists to demonstrate 
the fact or the nature of this hypothetical substance have 
failed; yet until the recently enunciated relativity theory 
it has not only been accepted by scientists as a necessity, 
but, on mathematical grounds many of its properties have 
been calculated. Thus Maxwell deduced figures expressive 
of its density, elasticity and rigidity, based upon its light 
carrying capacity, and expressed the opinion that it could 
not be of a grainy or discontinuous structure, but must 
be (as a whole) of the nature of an impalpable, imponder- 
able, invisible jelly-like mass, through which the heavenly 
bodies (including the earth) could move without creating 
friction. Further it is thought that this mass is constantly 
and in every part throbbing with undulations, which pro- 


418 Beacon Lights of Science 


duce and then instantly release, local stresses and strains, 
which in turn result in vortices, which it was suggested as 
perhaps capable of explaining the phenomena of electricity 
and magnetism. 

The relativity theory does not specifically deny the exis- 
tence of this assumed universal medium, any more than 
it denies the theory of gravitation, which is also a pure, 
assumption, and has never been demonstrated as a fact, 
though its properties have been calculated mathematically, 
like those of the ether. The theory simply asserts that 
neither are necessary, and that because it has been impos- 
sible so far to demonstrate in the slightest degree the exis- 
tence of either, it is not scientifically proper to assume it. 

It is certain that investigation of these two mysterious 
phenomena will not cease, and that new information about 
them will gradually accumulate. An enormous step in that 
direction has been taken in the resolution of matter into 
energy. The next will probably be as startling. The hu. 
man mind, now thoroughly awakened to its powers will not 
cease its questions of Nature so long as consciousness exists. 


ARRHENIUS (1859- _—s+)» 


CHEMISTRY 


SVANTE ARRHENIUS was born in the vicinity of Upsala, 
Sweden, and received the education of a chemist and physi- 
cian at the university in that city. After a few years of 
travel and study in Germany, Holland and France he was 
appointed to the chair of physiology at the University of 
Stockholm where, for the balance of his career, he taught 
and conducted research in that science and chemistry. He is 
regarded as the founder of the art of the electrical dissocia- 
tion of substances capable of carrying the electrical current 
when in the liquid state, into positive and negative ions. His 
investigations in this department of science have resulted 
in the development of valuable processes for the separation 
of many of the elements from their impurities, and from 
each other. 


The Nineteenth and Twentieth Centuries 419 


The particular service which he rendered to an art al- 
ready fairly well established on an experimental basis, was 
the discovery and enunciation of the laws governing the 
changes occurring in the processes of dissociation, so that, 
under given conditions, results could be accurately fore- 
told. Certain substances (common table salt, for instance) 
when dissolved in water, are found to be capable of earry- 
ing the electrical current, and, under proper conditions, 
will decompose into what are called ‘‘ions.’’ These are 
exceedingly minute particles of matter—not molecules, 
however,—which, according to the material of which they 
are composed, carry, or consist of a charge of either posi- 
tive or negative electricity ; that is, of either a proton or an 
electron. If now this ionized liquid be connected, through 
opposite sides of the vessel containing it, with the two 
terminals of a battery of any kind capable of producing 
an electrical current, a current will immediately be set up 
in the liquid itself, the negatively charged ions (the elec- 
trons) moving to the positive terminal of the battery (its 
anode), while the positively charged ones (the protons) 
go to the negative terminal (its cathode). The liquid it- 
self, when it has been brought into this state of electrical 
excitement, is called an electrolyte. Those ions which move 
to the anode have been given the name of anions. Those 
going to the cathode are called cations. One of the simplest 
examples of this act of dissociation is that of water, which 
is composed of the positive gaseous element hydrogen, and 
the negative elementary gas oxygen. When a current is 
passed through it decomposition at once begins, the hydro- 
gen ions moving to the negative terminal and those of 
oxygen to the positive one. If these terminals are of plati- 
num these gases, as they arrive, rise in bubbles to the sur- 
face of the liquid and float away. 

A more complicated example would be that in which 
the electrolyte was a molten bath of the mineral cryolite— 
a composition of the elements, sodium, aluminum and 
fluorine. This compound, when employed in the recovery 
of the metal aluminum, though an electrolyte, does not it- 
self undergo decomposition into ions under the influence 


420 Beacon Lights of Science 


of the electrical current. But it is capable, at the proper 
temperature, of dissolving alumina, the ore of the metal 
aluminum. When therefore that ore is added to a bath 
of molten cryolite held in a container lined with carbon, 
and the electric current turned on, the oxygen ions of the 
alumina pass to the positive pole of the battery (a earbon 
eylinder), uniting with it and forming carbon dioxide, 
while the abandoned ions of the metal sink to the floor of 
the vessel, to be later melted into commercial bars. This 
is the famous Hall process, which so reduced the cost of 
producing the metal that it became at once a desirable and 
much employed article of commerce. 


BRAGG (1862- _) 


PHYSICS 


WituiAM HENRY BRAGG was a native of the Isle of Man, 
which lies at the northern end of the Irish sea about equi- 
distant from the coasts of England, Ireland and Scotland. 
After acquiring his preliminary education at King Wil- 
liam’s College there, he entered and graduated at the Uni- 
versity of Cambridge with distinction in mathematics and 
physics. Shortly thereafter he was appointed professor of 
mathematics and physics at the Adelaide University in 
Australia, where his work was so highly satisfactory as to 
bring him in a few years the offer of the chair of physics 
at the University of London. 

In addition to ranking as an authority on the phenomena 
of sound which, for several years, he investigated ex- 
haustively, his outstanding accomplishment in research has 
been in connection with the properties of crystals, as ex- 
hibited in their capacities to diffract or break up into their 
component parts the Roentgen rays, in such a way as to 
explain the nature of that form of radiation, and at the 
same time the nature of the structure of crystals, two phe- 
nomena that for a number of years previously had been 
awaiting satisfactory elucidation. Roentgen rays may be 


The Nineteenth and Twentieth Centuries 421 


produced by bombarding plates of metallic tungsten or 
platinum with electrons to which a high velocity has been 
given by the electro-motive force of an induction coil, the 
process being carried out in the partial vacuum of an ex- 
hausted glass bulb. According to the investigations of 
Barkla—which have been amply verified—‘‘every sub- 
stance, under the proper stimulus, is capable of emitting 
such rays, which are characteristic of that particular ma- 
terial.’’ 

To understand properly the importance of these discov- 
eries, that valuable tool of the physicist called the ‘‘dif- 
fraction grating’’ will need to be recalled. In its con- 
struction the physical limit of delicate mechanical work had 
about been reached when one with 15,000 distinct and 
parallel lines to the inch had been successfully made by 
Rowland, and satisfactorily employed in measuring wave 
lengths. But even it was found to be unequal to the task 
of resolving the Roentgen ray. 

In 1912, Dr. Laue, of the University of Zurich, discovered 
the diffractive power of crystals. As this power depends 
upon the ordered arrangement of the atoms or molecules of 
which the crystal is composed; and as this arrangement is 
revealed by its external characteristics in the symmetrical 
faces, edges and angles that bound it, all of which are 
capable of measurement as to relative position, length, area 
and angular quantities, the internal structure may be 
analyzed ; and Laue succeeded in producing a mathematical 
expression which, as stated by Bragg, ‘‘gave the intensity 
at all points due to the diffraction of waves of known length 
incident on a set of particles arranged in a space lattice.’’ 

In following up this lead Bragg was the first to demon- 
strate that the Roentgen ray was identical in its nature 
with light, both being transverse undulations in the as- 
sumed ether of space; but with the difference that its wave 
length is about 1/5000 part of those in the visible spec- 
trum. At the same time he showed that ‘‘while the ordi- 
nary line grating would give a series of spectra at what- 
ever angle the incident rays fall upon it, the crystal, to 
produce a similar effect, must be interposed at exactly the 


422 Beacon Lights of Science 


right angle, and even then can only give a spectrum of one 
order at a time.’’ But, in the operation of the device, 
using the diverse faces of the erystals one after the other, 
the absolute wave length of the various types of the ray 
may be found; and, at the same time, equally exact infor- 
mation acquired as to the arrangement of the atoms or 
molecules in the body of the erystal employed. The im- 
portance of these conclusions ean hardly be overestimated. 
By them a path is indicated by which knowledge of the 
nature of atoms of the different elements has been gained, 
which is far-reaching in its implications as to atomic struc- 
ture in general. 

In 1914 Bragg was awarded the Barnard medal; and in 
the following year, in association with his son, who was 
his co-worker in the investigation, the Nobel prize in 
physics. 


ZEEMAN (1865-1922) 


PHYSICS 


PIETER ZEEMAN, a native of Zonnemaire in Holland, 
was educated at the University of Leyden. In 1900 he 
became professor of physics at the University of Amster- 
dam, and remained there in that capacity until his death. 

He was the discoverer, in 1897, of what is known as the 
‘‘Zeeman Effect,’? which brought him the Baumgartner 
prize in Vienna, the Wilde prize at Paris, and half the 
Nobel prize of 1902 in physics. 

The Zeeman effect consists of the doubling—or further 
multiplication—of the dark absorption lines of the spec- 
trum of a substance raised to a state of incandescence, 
when the substance, or the light so produced, is placed in, 
or passed through, a powerful magnetic field. Each line 
in the original spectrum is split up into two or more lines, 
when the source is examined from a direction at right 
angles to the lines of magnetic force, and also when viewed 
along the lines, but differently in the two eases. The light 
in these component lines is also polarized. The great im- 


The Nineteenth and Twentieth Centuries 423 


portance of the discovery lies in its bearing upon the ulti- 
mate cause of the vibrations of the ether which produce 
the sensation of light to the eye. The phenomenon seemed 
at the time to indicate that the actual source of these undu- 
lations is the vibrations of those minute portions of elec- 
trically charged matter which have been called electrons. 

And this has since been demonstrated to be the ease, 
although it is no longer regarded as correct to speak of 
‘‘minute portions of electrically charged matter’’ because 
it is now known that matter and electricity are identical, 
and that the former may be said to have disappeared in 
the latter. The discovery made by Zeeman then resolves 
itself in one of the earliest steps which led to this rather 
startling conclusion. By referring to the chapter devoted 
to Fraunhofer, it will be found that he was the discoverer 
in 1814 of the dark lines in the solar spectrum; which were 
not satisfactorily accounted for until 1859, when Kirchhoff 
and Bunsen took up the investigation, and showed that each 
one of them represented an element in the state of an in- 
ecandescent vapor in the outer layer of the body of the 
sun, through which the undulations emitted by its still 
more intensely heated inner surface had to pass before they 
could emerge into unoccupied space, and begin their long 
journey to the earth. 


STEINMETZ (1865-1923) 


ELECTRICITY 


CHARLES PROTEUS STEINMETZ (christened Karl Hein- 
rich) was born at Breslau in Germany. His father was an 
expert lithographer. The son received an excellent primary 
education, and entered the University of Breslau at the 
early age of seventeen. While a student there he became— 
like very many young Germans of his time—interested in 
the thoeries of socialism, as they had been set forth a gen- 
eration before by Karl Marx (1818-1883), and advocated 
them boldly, yet not fanatically. In his last and graduat- 
ing year he undertook temporarily the conduct of a social- 


424 Beacon [nights of Scrence 


ist periodical, while its editor was serving a term of im- 
prisonment for expressions regarded by the authorities as 
seditious, and himself incurred their displeasure. Antici- 
pating arrest, he managed to get across the border into 
Austria, and from there went to Switzerland, where he 
managed to earn his living by tutoring and in literary 
work at Zurich, at the same time attending the lectures at 
the technical school there, where he became acquainted and 
intimate with an American student. When the latter left 
for his home at the end of his course, Steinmetz decided 
to go with him. Traveling by the most inexpensive con- 
veyances, they took steerage passage at Havre, and landed 
in New York in June, 1889. Steinmetz had but $10 in his 
possession, and very little baggage, and was threatened 
with deportation as liable to become a public charge, be- 
cause of his unfortunate physical disability (curvature of 
the spine). His companion, however, was better fixed 
financially, and was able to show to the authorities a good 
sized roll of money, which he insisted was joint property. 
This resulted in the admission of Steinmetz. His first act 
was to take out his preliminary naturalization papers, 
which he completed as quickly as the provisions of the law 
allowed. 

Two weeks after landing he found employment as a 
draftsman in the establishment of Rudolf Hickemeyer at 
Yonkers, a manufacturer of general electric supplies and 
appliances, who was also beginning to specialize in the con- 
struction of electric cars. Here the value of his educa- 
tional equipment and inventive mind was quickly recog- 
nized, and while learning to speak English he made him- 
self so useful to his employer that when the latter, in 1892, 
sold his business to the General Electric Company, Stein- 
metz, by special agreement, went with it as a part of its 
‘‘oood will,’’ to the Lynn works of that organization. In 
the following year he was transferred to the plant at 
Schenectady where he remained for the balance of his life, 
becoming almost at once its highly valued consulting en- 
gineer. 

The scientific achievement with which his name will per- 


The Nineteenth and Twentieth Centuries 425 


haps be most associated is the explanation of the phenome- 
non of hysteresis in metals, and particularly of that variety 
of it caused by magnetism. Hysteresis was first observed 
by Warburg in 1881, and later independently by Ewing 
in 1885. These investigators observed that when a rod of 
iron had been converted by induction into a magnet, by 
being surrounded by a metallic coil or helix through which 
a current of electricity was passing, when the current was 
decreased in strength, or reversed, or stopped, demagneti- 
zation did not immediately decline or disappear; and that 
when interruption or change occurred in the current an ap- 
preciable time elapsed before the effect that should have re- 
sulted was produced. In other words there was a ‘‘lag’’ of 
effect, which was believed to be due to friction in the mole- 
cules of the bar, which revealed itself in a rise of its tem- 
perature. The ultimate effect is a loss of power which, in 
most forms of electrical machinery or installations, amounts 
in a short time to a notable decrease of efficiency. Stein- 
metz made an exhaustive study of this phenomenon, and in 
the end was able to devise means by which the most of the 
losses it caused could be obviated. 

In the early years of the science or art of electrical en- 
gineering, the direct current was universally employed. 
But as it advanced, it quickly became evident that advan- 
tages of importance could be gained by employing the alter- 
nating current, especially in long telegraph, telephone and 
power transmission lines, and ocean cables; and for all 
types of installations which operate most efficiently under 
a high voltage. But the laws under which the two varieties 
act, and the expression of them in formule, are very dif- 
ferent, those for the alternating or impulse current being 
much more complicated. Steinmetz undertook the simpli- 
fication of these, and being a mathematician of rare ability 
he succeeded to a very remarkable degree. Personally he 
regarded this as his chief accomplishment. 

He must be ranked also among the great inventors, hav- 
ing taken out some 200 patents, nearly all of them con- 
nected with the field of electrical engineering. Throughout 
his life he retained his belief and interest in socialism as 


426 Beacon Lights of Science 


a theory of communal life, and practiced it. While his 
views on the subject were definite and strong, they were 
never extreme, nor of a fanatical nature. He frankly ad- 
mitted that the world was not yet ready for the system, and 
would have to improve considerably in morality before it 
would be. He never ceased to be thankful—and to give 
expression to it—that he had been permitted to become a 
citizen of a land where views such as he held could be 
retained and expressed freely, without incurring political 
persecution and loss of standing as a citizen and patriot. 


CURIE (1867-__—+) 


CHEMISTRY 


MARIE CURIE was born at Warsaw, Poland, her father, 
Dr. Sklodowski, having been an instructor in general sci- 
ence in the local gymnasium (the name given in central 
Europe to the high schools where students are prepared 
for the universities). Often the young girl was his assis- 
tant in the laboratory, at first only in keeping the place 
in order and in cleaning the glass beakers, test tubes, ete., 
used in experimnetal work. But as she grew up and ab- 
sorbed in school the fundamental principles of science, she 
became so deeply interested in chemistry as to be able to act 
as his assistant in preparing his experiments, and in earry- 
ing them on while he was delivering his lectures. Mean. 
time her general education in school was advancing rapidly. 

At this period of her life that part of the ancient king- 
dom of Poland in which she lived was a province of Rus- 
sia, and under severe repression. ‘'T'o escape this, and hav- 
ing meantime earned and saved enough by work as a gov- 
erness for several years, she went to Paris in 1885, and 
secured employment at that great institution of learning 
then and since known as the Sorbonne. Her work at first 
was only that which she had performed for her father in 
the early days of her service in his laboratory, but in a 
short time her knowledge of chemistry, and her experience 
in it beeame known, and she was advanced to the position 


The Nineteenth and Twentieth Centuries 427 


of assistant to Pierre Curie, one of the research students 
there, who in 1895 became her husband. His interests at 
the time were mainly in the subjects of physics and elec- 
tricity, while hers were to secure her degree. This she 
finally won with distinction in 1898. 

In 1896 the French chemist Becquerel made his impor- 
tant discovery of the mysterious emanations that are con- 
stantly given off by ores and compounds of the compara- 
tively rare element uranium, which have the power of 
penetrating many substances opaque to light, and of af- 
fecting the photographie plate in the same way as the 
Roentgen ray and the actinic rays of white sunlight. As 
will be seen in the chapter devoted to him he did not follow 
up the matter, but Mme. Curie became greatly interested 
in it, and after a certain amount of preliminary investiga- 
tion with that ore of uranium called pitchblende, which is 
found in fair abundance in several of the European mining 
districts—notably in Bohemia, Cornwall and Norway— 
reached the conclusion that the Beequerel emanations did 
not come from that metal, but from some as yet unknown 
substance associated with it. At the time her husband 
was engaged in an investigation in physics, but this was 
temporarily set aside, and the two took up the new line of 
research, which culminated in 1898 in the discovery by 
them in the ore of two new elements, to one of which they 
gave the name of radium, and to the other that of polonium 
(in honor of her native land). These have since been 
shown to exist in all ores of uranium, and to be the prod- 
uct of its constant devolution. But, as they are themselves 
also constantly undergoing degradation or decomposition 
into other elementary conditions, they exist in quantities 
so comparatively minute that to secure enough for experi- 
mental purposes it was determined that a ton of the 
pitchblende ore must be obtained to work on. This was 
contributed by the Austrian government from one of its 
Bohemian mines, and after operating for nearly four years, 
Mme. Curie in 1903, in a thesis delivered at the Sorbonne, 
gave a description of the process by which the two new 
elements had been extracted from it, a statement of their 


428 Beacon Lights of Scrence 


properties as far as then ascertained, and a sample of both 
in the form of chlorides. For this achievement they were 
awarded the Davy medal of the Royal Society of London, 
and half of the Nobel prize of $40,000 in chemistry for that 
year, the other half very properly going to Becquerel. In 
1906 her husband was accidentally killed by being run over 
in one of the crowded streets of Paris by a heavy truck. 
Mme. Curie, by then the mother of two children, disre- 
garding this severe bereavement, continued her work on 
the two metals, and in 1910 succeeded in isolating radium 
in its metallic condition, and in determining its atomic 
weight and some of its properties. For this remarkable 
feat she was given the full amount of the Nobel prize in 
chemistry for that year. Simultaneously her name was 
presented for membership in the French Academy of Sci- 
ences, perhaps the most exclusive and notable society of 
its kind in the world but, on account of her sex, failed of 
election; a result which has since been deeply regretted by 
scientists everywhere. In 1915 a Radium Institute was 
organized in Paris, and Mme. Curie placed at its head, a 
position she has retained ever since with credit to herself, 
and great advantage to the rest of the world. 

Radium is a true metal of a lustrous silver-white color, 
which melts at 700 degrees C., and tarnishes rapidly in the 
air. Its atomic weight is 226.5. Its place in the Periodic 
Table of the elements is in the vertical group which begins 
with beryllium and is followed in order by magnesium, eal- 
cium, zinc, strontium, cadmium, barium and mercury. Its 
atomic number is 89. It occurs in nature in all the ores 
of uranium and thorium, but in a very minute quantity. 
In a metric ton of pitchblende (which contains roughly 60 
per cent of uranium) a shade over three grains (a tea- 
spoonful) exists. To obtain the gram of radium chloride 
which was presented to Mme. Curie by the women of 
America in 1921, required the concentration of 600 tons of 
carnotite—one of its ores that is quite abundant in Colo- 
rado and Utah—and several months of laboratory work. 
Its high cost is thus easily apparent. The recovery of it 
without serious loss is a long and delicate process. As, one 


The Nineteenth and Toneniseeh Centuries 429 


by one, the numerous other elements associated with it are 
eliminated, the residues become at each stage more power- 
fully radio-active, and towards the end dangerously so, for 
the emanations, unless properly controlled, are exceedingly 
corrosive to human flesh, while at the same time when some 
of them.are cut off by suitable screens, have been found to 
be of help in destroying or temporarily weakening the 
erowths of cancerous cells. The element does not come on 
the market in its metallic condition, for in that form it is 
chemically very unstable and hence unusable. But in the 
condition of the chloride or bromide it is chemically stable, 
while its radio-activity is as great as when in the metallic 
state. Polonium has not yet been isolated as a metal, but 
its atomic weight has been ascertained as about 222. It 
exists in quantities even more minute than radium. In 
addition to these two, the French chemist Debierne in 1899 
found another radio-active element, to which he gave the 
name of actinium, and in 1907 Boltwood added a fourth to 
the list, which he called ionium. These three, however, ap- 
pear to be simply members of a long list of disintegration 
products, a few of which possess enough inherent chemical 
stability to live for periods that may be expressed in years, 
but the most of them perish in a few days, or in a few 
minutes, or, in the ease of four or five, their brief existence 
is measurable only in seconds. 

The significance of the discovery of radium lies in the 
fact that it opened an entirely new field of research in 
science. Previously the chemical atom had been regarded 
as indestructible. Now it has become evident that at least 
the three heaviest of the known list are constantly under- 
going a process of disintegration or devolution. Ever since 
the day of Dalton (1766-1844), whose work established the 
atomic theory, the belief has been held by many chemists 
that all of them are, in some way, but combinations of one 
of them—the lightest, hydrogen. This belief is stronger 
today than ever, though it is not yet proved. But the 
process of the devolution of the heavier element has now 
been established by the researches and discoveries of the 
Curies and those who have followed up their lead. If 


430 Beacon Lights of Science 


some can and do break up into elements of lower weight 
and less complexity of structure, it is plausibly reasoned 
that ultimately it will be demonstrated that all have been 
built up in the past; that the ultimate chemical particles 
of matter themselves are as subject in their most funda- 
mental aspect to the great law of evolution, as those higher 
and more complex forms of it which we eall organic life. 
The recent discoveries by which the chemical elements 
have been shown to consist of nothing more than units of 
positive and negative electricity (pure energy) combined 
in various ways, has converted the expectations of the 
early chemist into something akin to certainty in the minds 
of those of today. 


MARCONI (1874 i+) 


ELECTRICITY 


GUGLIELMO MARcONI was born in the vicinity of the city 
of Bologna, Italy, his father having been a native of that 
country and his mother of Ireland. The family were large 
landed proprietors. His education in youth was under 
private tutors, one of whom, Professor Righi, was a scien- 
tist of some note. It was in 1886 that the German physi- 
cist Hertz began the series of experiments which, in the 
year following, revealed the existence of those electro- 
magnetic undulations in the ether that had been postulated 
a quarter of a century before by the Scotch mathematician 
Maxwell, in his study of the nature of light. Young Mar- 
coni, then under fourteen years of age, became deeply in- 
terested in the published accounts of the discoveries, and 
repeated on his father’s estate with crude aerials some of 
the experiments of the German, thus becoming the first 
radio enthusiast. As is often the case with men of science, 
Hertz made little if any attempts to put his discovery into 
practical use, but Marconi possessed the character of the 
practical inventor. Connecting one terminal of his induc- 
tion coil to the sending aerial, he grounded the other, which 
had the effect of greatly increasing the capacity of his 


The Nineteenth and Twentieth Centuries 431 


oscillator to produce the Hertzian waves. With this prim- 
itive installation, and using a simple form of resonator, he 
was soon able to send signals through several hundred feet 
of distance. From these small beginnings, improved year 
by year as he gained knowledge and experience, he ad- 
vanced step by step in the path of his ambition until, in 
1899, he established wireless communication across the Eng- 
lish channel, and in the following year was sending and 
receiving Hertzian wave signals over much of western 
Europe. 

By this time he had sold to the British government, and 
to several other nations, the right to use his patents, and 
the great value of his invention for establishing communi- 
cation between vessels at sea, and between them and near 
coast stations, had been amply demonstrated. Many im- 
periled ships had been rescued. It had been learned that 
longer distances could be bridged by the construction and 
use of loftier aerial terminals; and so, in 1901, abandoning 
the narrow field of Europe, he turned his attention to the 
problem of establishing communication with the New 
World. At Poldhu, on the western coast of Cornwall, he 
had erected a sending station 210 feet in height, and 
equipped it with powerful operating machinery and appli- 
ances. 

In December of that year he landed on the eastern coast 
of Newfoundland. There, using for an aerial the metal 
string of a kite which, after great effort, had been raised 
to and held at an approximate elevation of 400 feet, he re- 
ceived on the 12th of that month the first wireless signals 
across the 2000 miles of water, in the form of the three 
dot clicks of the Morse code which stand for the letter S; 
which the Poldhu operator had been directed to send out 
daily at an agreed hour. Their detection was effected by 
the use of an ordinary telephone receiver. 

In 1914 Marconi was awarded the medal of the Franklin 
Society of America for his discoveries in the radio art. In 
the years that have followed his achievement in bridging 
the Atlantic, wireless has advanced with startling rapidity. 
In the Great War it was a terrible aid to destruction, but 


- 432 Beacon Laghts of Scrence 


since then has been extended around the world in benefi- 
cence. In its development many new discoveries of impor- 
tance have been made, so that today a wireless installation 
is a vastly different affair even from that notable one at 
Poldhu which had a range of two thousand miles. The 
coherer has been replaced by the erystal detector, which 
passes the Hertzian waves in one direction only, and con- 
verts the oscillation current of the antennae into a direct 
pulsation quite capable of producing audible signals in the 
Edison telephone receiver. For the induction coil, the 
vacuum tube detector and amplifier has been substituted. 
Generators and transformers have been vastly improved. 
Kvery step has been a marvel of advance, and the end that 
may be achieved is not yet in sight. In justice to the still 
young scientist the information should be published as 
widely as possible that he has never attempted communica- 
tion with Mars. All statements to that effect have been 
manufactured out of the whole cloth. 


EINSTEIN (1875-__—i+) 


PHYSICS 


ALBERT EINSTEIN, of Jewish ancestry, was born in 
Switzerland. He received an excellent education, and grad- 
uated with honor at the University of Zurich. Subse- 
quently he was a professor there, and later occupied the 
chair of mathematics at the University of Prague. After- ° 
wards he became a member of the faculty of the University 
of Berlin. While holding this last position he published, 
in 1905, his first essay, on the Special Theory of Relativity. 
Very little notice of it was taken at the time. When the 
Great War broke out in 1914, and the professional class in 
Germany joined in a public protest against the opinion 
then universally held throughout the rest of the world that 
the action was unwarranted, Einstein was one of the few 
scientists of the nation that refused to sign it. In conse- 
quence of the disfavor with the authorities into which this 
action plunged him, he resigned his position and returned 


The Nineteenth and Twentieth Centuries 433. 


to Switzerland, where he remained throughout the contest. 
At its termination he was invited to return and resume 
his post at Berlin. Since then that city has been his home. 
And from there, in 1919, he published his General Theory 
of Relativity, which at once attracted the attention of the 
civilized world. 

It will be impossible in the brief space that can be given 
in this volume to the story of his life, to do more than 
indicate the outline of his theory, and the conclusions he 
has reached. He is, above all things, a mathematician, and 
of a very high order. Such people think and speak in a 
language not understood by the average well educated indi- 
vidual, and commit their results to paper by the use of 
symbols with which he is generally totally unfamiliar. One 
of his most lucid commentators (Heyl), comparing his 
theory with that of Sir Isaac Newton says: ‘‘Where New- 
ton’s law takes the form of a single differential equation, 
that of Einstein is expressed by a set of ten simultaneous 
differential equations, each of so fearful and wonderful a 
structure that a most compact and unfamiliar notation is 
required to render it fit to print.’’ Under such conditions 
no attempt will be made to translate his law into intelligible 
language. It would be, in fact, impossible to do it. 

Nevertheless, his conclusions have so far been verified in 
two crucial tests, and can hardly be denied. Moreover, 
none of these do more than to add to those concepts of the 
nature of the universe which, for the last two centuries 
have been regarded as settled. They do not contradict or 
upset them, as has been too often claimed. On the con- 
trary they support them up to a certain limit, and then, for 
reasons not difficult to grasp, assert that in consequence of 
the advance of knowledge during this period, the law can 
and should be stated in a more correct way. 

Over sixty years ago Herbert Spencer, in an essay en- 
titled ‘‘The Relativity of all Knowledge,’’ gave clear and 
definite expression to the fundamental idea of Einstein’s 
theory. It was not original with the latter, nor does he 
claim it to have been. 

Heretofore those concepts which are called by the names 


434 Beacon Lights of Science 


of Space and Time have been regarded as absolute ones in 
their nature, representing actual facts; the former, an ex- 
tension in all directions along straight lines to infinity, and 
the latter eternally into the past in one direction and into 
the future in another. No philosopher has yet arisen who 
has been able to form even mental pictures of these con- 
cepts, or to express their meaning in language. Neverthe- 
less they have been accepted as truths. Einstein asserts, in 
effect, that Space is a relative concept, and instead of pos- 
sessing the quality of indefinite lnear extension, is that of 
curvilinear extension, which ultimately returns to itself. 
It may be likened to the summation of those innumerable 
lines on the surface of a perfect sphere which are called 
‘‘oreat circles,’’ each of which represents the shortest dis- 
tance between points along it, on the curving surface. With 
him Time is but the place which a three-dimensional body 
occupies during each instant of its existence, and which, 
when considered in connection with those lines of direction 
which are called length, breadth and thickness, constitutes 
the fourth dimension, which he asserts to be the measure- 
ments of reality. Or, to put the matter in a different way, 
the four dimensions are—up and down, forward and back- 
ward, to the right and to the left, and towards the past 
and towards the future. Only by including the last, can 
the position of any point or event in space be accurately lo- 
cated. 

Newton postulated a force (gravitation) to explain the 
fall of the apple, and stated the law of its operation. EHin- 
stein denies that such a force exists, but admits that the 
law which Newton enunciated is, for all practical purposes, 
a correct one, for all bodies in Space and Time as hereto- 
fore conceived. But, under the new conception of them it 
does not explain observed phenomena with absolute accu- 
racy, when enormous distances and prolonged periods of 
time are involved. Under the latter conditions the element 
of curvature in Space, and its four-dimensional nature, 
compel a modification of the law. 

Although many attempts have been made to account for 
the apparent fact of gravitation, no success has been at- 


The Nineteenth and Twentieth Centuries 435 


tained. Similarly, the nature of that directly opposing ap- 
parent fact called centrifugal force remains wholly unex- 
plained. Einstein denies the existence of both, as forces, 
thus accounting easily for the the difficulties experienced 
in trying to understand them. His contention is that they 
are no more than manifestations of that property of matter 
which is called inertia. 

According to Newton, if a body is left to itself; it falls 
through space to the earth, in consequence of the force of 
gravitation. According to Einstein, the same body under 
identical conditions, falls through time-space along the 
shortest possible track. This, when the distance is small, 
is apparently that of a straight line, but when great, is that 
of a curve, which ultimately will return to itself if suffi- 
ciently prolonged. Gravitation and centrifugal force are 
then simply two aspects of the one entity, inertia. Both, 
as Heyl says, are ‘‘independent of the material, are not 
functions of temperature, and cannot be cut off by any 
form of screen. In fact, they seem to be functions only 
of the mass involved, and the space (and time) co-ordinates 
of the system.’’ In other words they are not forces, but 
properties of the concept of mass. What then is mass? 
Until recently it has been defined as the quantity of mat- 
ter (expressed in terms of weight) contained in any given 
volume of three-dimensional space. If, for the final word 
in this definition we substitute time-space, and at the same 
time remember that the latest discoveries in connection 
with the chemical atom has revealed it as simply a center 
of force, of the nature of one or more units of the two forms 
or manifesiations of electrical energy (protons and elec- 
trons), it seems inevitable that the hitherto accepted defi- 
nition of mass must be changed. For that component of 
it which has been called weight, and has been regarded as 
a purely gravitational effect, must now be substituted iner- 
tia, which, in its manifestation of centrifugal force, in- 
volves or implies the total absence of weight. And for 
volume of three-dimensional space, a corresponding bulk 
of time-space. These adjustments being made, the revised 
conception of the universe according to the theory of Rela- 


436 Beacon Lights of Science 


tivity, begin to seem more reasonable and comprehensible. 

There is but one pure (perfect) department of science; 
but one collection and organization of facts which, so far 
as it has been developed, has never required correction or 
revision. That is the science of numbers (mathematics). 
Conclusions correctly reached in its domain must be re- 
garded as final statements of truth, no matter where they 
lead. The Einstein conclusions appear so far to be of such 
a character and, if so, incapable of denial. It is too early, 
however, to predicate his final place and rank among the 
masters of science. There are just as vigorous opponents 
as proponents of his theories. Nevertheless we can safely 
give him credit for presenting the most radical, and there- 
fore the most interesting of new hypotheses, since Newton 
in 1687 gave to the world the law which apparently still 
controls the motion of the earth and all the heavenly bodies 
in. space, 


A 


Abbe, Cleveland, 380 
Abel, Niels Henrik, 275 
Adams, John C., 310 
Aeronautics: 
Charles, J. A., 186 
Montgolfier, 187 
Blanchard, 187 
Langley, 367 
Aesculapius, 11 
Agassiz, Louis, 282 
Ahmes, 36 
Alemaeon, 34 
Alexander, 15, 20 
Algebra, 35 
Al Hazen, 45 
Al Khuwarismi, 43 
Ampere, André M., 223 
Anatomy: 
Erasistratus, 18 
Galen, 33, 69, 71 
Fallopius, 62, 71 
Vesalius, 68, 71 
Hipparchus, 69 
Da Vinci, 57 
EKustacio, 71 
Fabrizio, 72 
Harvey, 72, 99 
Malpighi, 119 
Hunter, 161, 195 
Spellanzoni, 164 
Galvani, 174 
Jenner, 195 
Cuvier, 213 
Bell, 222 
Von Baer, 255 
Weber, 259 
Miler, 273 


INDEX 


Pacini, 297 

Bernard, 300 

Broca, 339 

Kovalevsky, 385 
Anaximander, 4 
Andrews, Thomas, 291 
Angstrom, Anders J., 303 
Apollonius, 26 
Arago, Dominique, 245 
Archimedes, 21 
Aristarchus, 24 
Aristotle, 4, 18, 14, 17, 34 
Arrhenius, Svante, 418 
Aryabhatta, 36, 41 
Astronomy : 

Pythagoras, 5 

Eratosthenes, 23 

Aristarchus, 24 

Hipparchus, 27 

Aryabhatta, 41 

Copernicus, 58 

Brahe, Tycho, 76 

Hainzel, 77 

Galileo, 85 

Kepler, 94 

Cassini, 118 

Halley, 135 

Bradley, 136 

Herschel, 175 

Bode, 190 

Laplace, 198 

Gauss, 229 

Piazzi, 229 

Legendre, 230 

Adrian, 230 

Bessel, 241 

Arago, 245 

Leverrier, 294 

Challis, 295 


437 


438 


Astronomy Cont’d: 
Adams, 310 
Huggins, 340 
Lockyer, 373 
Hill, 375 

Audubon, John J., 237 

Avebury, Lord, 364 


Aviation. See Aeronautics. 


Avogadro, Amadeo, 225 


B 


Bacon, Roger, 48 
Bacteriology: 

Pasteur, 327 

Koch, 390 

Miller, 391 
Bates, Henry W., 343 
Becquerel, Antoine H., 411 
Bell, Charles, 222 
Bernard, Claude, 300 
Bernouilli, Daniel, 146 
Berthelot, Pierre, 349 
Berthollet, Claude, 193 
Berzelius, Jons J., 234 
Bessel, Friedrich W., 241 
Bhaskara, 46 
Biology: 

Darwin, 286 

Miiller, 315 

Galton, 320 

Mendel, 324 

Schulze, 342 

Huxley, 345 

Tylor, 358 

Metchnikoff, 396 
Black, Joseph, 162 
Blanchard, 187 
Bode, Johann, 190 
Boethius, 42 
Boltzmann, Ludwig, 394 
Botany: 

Theophrastus, 17 

Dioscorides, 17, 29 

De Jussieu, 140, 183 

Brown, 219 

Schlieden, 220 


Index 


Gray, 289 

Hooker, 306 
Boyle, Robert, 116 
Bradley, James, 136 
Bragg, William H., 
Brahe, Tycho, 76, 95 
Brahmagupta, 42 
Brewster, David, 239 
Broca, Paul, 339 
Brown, Robert, 219 
Buckland, Francis T., 347 
Buddha, 47 
Buffon, Comte de, 150 
Bunsen, Robert W., 295 


C 


Calculus, 22, 109, 138 
Capillarity, 157 
Cardano, Girolamo, 67 
Cassini, Giovanni, 118 
Cavendish, Henry, 166 
Charles, Jacques, 186 
Chemistry: 
Boyle, 116 
Gray, 145 
Black, 162 
Cavendish, 166 
Priestley, 167 
Scheele, 177 
Lavoisier, 181 
Volta, 184 
Berthollet, 193 
Proust, 204 
Fischer, 205 
Wollaston, 209 
Fraunhofer, 209 
Osann, 211 
Claus, 211 
Dalton, 211 
Davy, 231 
Gay-Lussac, 232 
Berzelius, 234 
Dulong, 242 
Cheyreul, 243 
Dumas, 269 
Wohler, 271 


Chemistry Cont’d: 
Liebig, 272, 279 
Andrews, 291 
Van Marum, 292 
Draper, 293 
Berthelot, 349 
Kekulé, 353 
Nobel, 362 
Mendeleef, 368 
Perkin, 377 
Moissan, 405 
Fischer, 406 
Ramsay, 408 
Van’t Hoff, 412 
Arrhenius, 418 
Curie, 426 
Becquerel, 427 
Dalton, 429 

Chevreul, Michel E., 243 

Chladni, Ernest, 207 

Cicero, 22 

Clairault, Alexis, 156 

Clausius, Rudolf, 325 

Clavius, 55 

‘“Conic Sections,’’? 22 

Cope, Edward D., 383 

Copernicus, Nikolaus, 58 

Coral, 299 

Cosmology: 

Ptolemy, 30 
Coulomb, Charles, 169 
Crookes, William, 360 
Curie, Marie, 426 
Cuvier, Georges, 213 


D 


Daguerre, Louis, 251 
D’Alembert, 158 

Dalton, John, 211 

Dana, James Dwight, 298 
Darwin, Charles R., 286 
Da Vinci, Leonardo, 50, 56 
Davy, Humphry, 231, 253 
Democritus, 9 
Demosthenes, 13 
Desargues, Gerard, 103 


Index 439 


Descartes, René, 104 
Dewar, James, 388 
Diderot, 159 

Diophantus, 35 

Dioscorides, 17, 29 
Doppler, Christian, 278 
Draco, 12 

Draper, John William, 293 
Dulong, Pierre Louis, 242 
Dumas, Jean Baptiste, 269 


E 


Edison, Thomas A., 400 
Einstein, Albert, 432 
Electricity: 
Franklin, 148 
Ampere, 223 
Ohm, 248 
Faraday, 253 
Henry, 264 
Morse, 265 
Wheatstone, 277 
Edison, 400 
Thomson, 414 
Steinmetz, 423 
Marconi, 430 
Electro-chemistry:? 
Volta, 184 
Embryology: 
Von Baer, 255 
His, William, 256 
(Also see Anatomy) 
Empedocles, 8, 16 
Energy, 308, 317 
Epicurus, 10 
Erasistratus, 18 
Erastosthenes, 23 
Euclid, 19 
Eudoxus, 13 
Euler, Leonhard, 154 
Eustacio, Bartolomeo, 71 
Evolution: 
Empedocles, 8 
Aristotle, 16 
Darwin, 286 
Haeckel, 370 
Explosives, 362 


440 


F 


Fabre, Jean H. C., 331 
Fabrizio, Girolamo, 72 
Faraday, Michael, 253 
Fallopius, Gabriel le, 62 
Fermat, Pierre de, 109 
Fibonacci, 42 

Fischer, Emil, 406 
Fizeau, 309 

Forbes, James D., 287, 292 
Foucault, Jean, 309 
Franklin, Benjamin, 148 
Fresnel, Augustin J., 250 
Fraunhofer, Joseph, 247 


G 


Galen, 33, 69 
Galileo, 85 
Galton, Francis, 320 
Galvani, Luigi, 174, 184 
Galvanometer, 218 
Gauss, Karl F., 229 
Gay-Lussac, Louis J., 232 
Geography: 

Ptolemy, 30 

Maury, 281 

Guyot, 284 
Geology: 

Hutton, 160 

Playfair, 161 

Smith, 161 

Lyell, 161 

Werner, 192 

Silliman, 235 

Lyell, 263 

Murchison, 263 

Agassiz, 282 

Forbes, 282 

Guyot, 282 

Michel-Levy, 392 
Geometry, 188, 258 
Gesner, Konrad von, 70 
Gibbs, Josiah W., 381 
Gilbert, William, 74, 170 
Gray, Asa, 289 


Index 


Gray, Stephen, 145 
Gregory XIII, 55 
Guericke, Otto von, 111 
Guyot, Arnold, 282, 284 


H 


Haeckel, Ernest H., 370 

Halley, Edmund, 135 

Haroun al Raschid, 20 

Harvey, William, 35, 99 

Hauy, René, 179 

Heat, 317 

Helmholtz, Herman L. F. von, 
316 

Henry, Joseph, 264 

Herschel, William, 175 


, Hertz, Heinrich, 416 


Hill, George William, 375 
His, William, 256 
Hipparchus, 27, 69 
Hippocrates, 11 . 
Hittorf, Johann W., 334 
Hooke, Robert, 124 
Hooker, Joseph D., 306 
Huggins, William, 340 
Humboldt, Alex. von, 215 
Hunter, John, 161 
Hutton, James, 160 
Huygens, Christian, 120 
Huxley, Thomas Henry, 345 


J 


Jenner, Edward, 195 
Joule, raion P., 307 
Tussiew, Bernard de, 140, 183 


K 


Kekulé, Friedrich A., 353 
Kelvin, Lord, 337 

Kepler, John,.94 

Kirchoff, Gustav R., 336 
Koch, Robert, 390 + 
Kovalevsky, Alexander, 385 


Index 


L 


Lagrange, Joseph, 173 
Lamarck, Jean B., 182 
Langley, Samuel P., 367 
Laplace, Pierre, 198 
Lavoisier, Antoine, 181, 193 
Leeuwenhoek, Antonius van, 114, 
122 
Legendre, Adrien, 200 
Leidy, Joseph, 528 
Leibnitz, G. W. von, 132 
Leverrier, Urbain, 294 
Liebig, Justus, 279 
Light, aberration of, 136 
Light, velocity of, 131 
Linnaeus, Carolus, 17, 152 
Lister, Joseph, 351 
Lobatchewsky, Nicolai, 258 
Lockyer, Joseph N., 373 
Logarithms, 84, 206 
Lubbock, John, 364 
Lycurgus, 13 
Lyell, Charles, 161, 263 


M 


Maclaurin, Colin, 138 
Malpighi, Marcello, 119 
Marconi, Guglielmo, 430 
Marco Polo, 217 
Marsh, Othniel C., 354 
Marx, Karl, 425 
Mathematics: 

Anaximander, 4 

Plato, 12 

Euclid, 19 

Apollonius, 26 

Diaphantus, 35 

Brahmagupta, 42 

Boethius, 42 

Fibonacci, 42 

Al Khuwarismi, 43 

Al Hazen, 45 

Stevin, 43 

Bhaskara, 43, 46 


44] 


Al Kinde, 44 

Peuerbach, 52 

Miller, 53 

Tartaglia, 67 

Cardano, 67 

Stevin, 82 

Napier, 83 

Desargues, 103 

Descartes, 104 

Fermat, 109 

Pascal, 114 

Leibnitz, 132 

Maclaurin, 138 

Bernouilli, 146 

Euler, 154 

D’Alembert, 158 

Playfair, 161 

Monge, 188 

Legendre, 200 

Prony, 205 

Lobatchevsky, 258 

Abel, 275 

Jacobi, 275 

Newcomb, 371 

Gibbs, 381 
Maury, Matthew F., 281 
Maxwell, James Clark, 357 
Mechanics: 

Archimedes, 21 

(Also see Physics) 
Medicine: 

Hippocrates, 11 

Lister, 351 

(Also see Anatomy) 
Mendel, George J., 324 
Mendeleef, Dimitri I., 368 
Mersenne, Marin, 101 
Metchnikoff, Iliya, 396 
Meteorology, 380 
Michel-Levy, Augustus, 392 
Microscopy: 

See Physics 
Mineralogy: 

Hauy, 179 

(Also see Geology) 
Mohammed, 45 
Moissan, Henri, 405 


442 


Monge, Gaspard, 188 


Miiller, Johannes, (Regiomon- 


tanus), 53, 59 
Miiller, Johannes, 273 
Miiller, Johann F. T., 315 
Murchison, Roderick, 263 


N 


Napier, John, 83 

Natural History: 
Gesner, 70 
Aldrovandi, 70 
Buffon, 70, 150 
Linnaeus, 70, 152 
Lamarck, 182 
Cuvier, 214 
Humboldt, 215 
Audubon, 237 
Dana, 298 
Wallace, 321 
Leidy, 328 
Fabre, 331 
Bates, 343 
Buckland, 347 
Marsh, 354 
Lubbock, 364 
Weismann, 365 
Cope, 383 

Naiural Science: 
Democritus, 9 
Aristotle, 14 
Bacon, 48 
Da Vinci, 56 
(See also Physics) 

Newcomb, Simon, 371 

Newton, Isaac, 126 

Nobel, Alfred B., 362 


O 


Oersted, Hans C., 217 
Ohm, George S., 248 
Ozone, 292 


Index 


P 


Pacini, Filippo, 297 
Pascal, Blaise, 114 
Pasteur, Louis, 327 
Pathology: 
Virchow, 318 
(See also Medicine and Ana- 
tomy) 
Peripatetics, 17 
Perkin, William H., 377 
Peuerbach, George von, 52 
Philosophy: 
Plato, 12 
Bacon, 48 
Leibnitz, 132 
Photography: 
Daguerre, 251 
Draper, 252 
Physics: 
Archimedes, 21 
Mersenne, 101 
Pythagoras, 102 
Rayleigh, 102 
Chladni, 102 
Guericke, 111 
Torricelli, 112 
Leeuwenhoek, 114 
Huygens, 120, 122 
Hooke, 124 
Newton, 126, 433 
Clairault, 156 
Coulomb, 169 
Thomson, 170 
Gilbert, 170 
Watt, 171 
Lagrange, 173 
Rumford, 202 
Stahl, 203 
Chladni, 207 
Oersted, 217 
Young, 221 
Avogadro, 225 
Brewster, 239 
Wheatstone, 239 
Fraunhofer, 247 
Wollaston, 248 


Physics Cont’d: 
Fresnel, 250 
Daguerre, 251 
Sadi-Carnot, 261 
Wheatstone, 277 
Doppler, 278 
Forbes, 287 
Von Mayer, 301 
Angstrom, 303 
Langley, 305 
Rubens, 305 
Joule, 307 
Foucault, 309 
Roemer, 131, 209 
Fizeau, 209 
Stokes, 311 
Tyndall, 313 
Helmholtz, 316 
Galton, 320 
Clausius, 325 
Hittorf, 334 
Kirchoff, 336 
Thomson, 337 
Maxwell, 357 
Crookes, 360 
Abbe, 380 
Rayleigh, 386 
Dewar, 388 
Boltzmann, 394 
Wroblewski, 397 
Roentgen, 399 
Rowland, 403 
Becquerel, 411 
Hertz, 416 
Bragg, 420 
Zeeman, 422 
Einstein, 432 
Spencer, 433 


Physiology. See Anatomy. 


Plato,-12, 17 

Playfair, 161 
Polybus, 12 

Priestley, Joseph, 167 
Primitive Theories, 3 
Prony, Gaspard, 205 
Proust, Joseph L., 204 
Ptolemy, 30 


Index 443 


Ptolemy Philadelphus, 27 
Pythagoras, 5, 61 


R 


Radium, 428 

Ramsay, William, 408 
Rayleigh, Lord, 386 
Regiomontanus, 53 
Relativity, 432 

Roemer, Olaus, 131, 309 
Roentgen, Wilhelm K., 399 
Rowland, Henry A., 403 
Rumford, Count, 202 


8 


Sadi-Carnot, Nicholas L., 261 
Scheele, Carl W., 177 
Schulze, Max J. S., 342 
Silliman, Benj., 235 

Sines, 52 

Sixtus IV, 59 

Smith, William, 161 
Socrates, 12 

Spectrum analysis, 303 
Spellanzani, Lazaro, 164 
Steinmetz, Charles P., 423 
Stereoscope, 239 

Stevin, Simon, 82 

Stokes, George G., 311 
Strutt, John W., 386 


i 


Tartaglia, Nicolo, 67 
Telescope, 86 

Thales, 3 

Theon, 27 

Theophrastus, 17 

Thesalus, 12 

Thompson, Benjamin, 202 
Thomson, Joseph J., 170, 414 
Thomson, William, 219, 337 
Torricelli, Evangelista, 112 
Tyndall, John, 313 

Tylor, Edward B., 358 


AAA 


Vv 


Van’t Hoff, J. H., 412 
Vesalius, Andreas, 68 
Virchow, Rudolph, 318 
Volta, Alessandro, 184 
Von Baer, Karl E., 255 
Von Mayer, Julius R., 301 


Ww 


Wallace, Alfred Russel, 321 
Watt, James, 171 

Weber, Ernest H., 259 
Weismann, August, 365 


Index 


Werner, Abraham, 192 
Wheatstone, Charles, 277 
Wohler, Friedrich, 271 
Wollaston, William H., 209 
Wroblewski, Z. F., 397 


4 


Young, Thomas, 221 


Z 


Zeeman, Pieter, 422 
Zodlogy. See Natural History. 








dou a 4 


ay 

















LINOIS-URBANA 


L 


F 


oO 
> 
a 






























































